From 0aa85f2cca34f33c62b9e24a148edc5dd7d33484 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Mon, 28 Oct 2024 06:02:31 +0100
Subject: [PATCH 01/49] Added PyQt6 widget and added ax kwarg to the visualize
 methods

---
 src/iminuit/cost.py     | 107 +++++++---
 src/iminuit/minuit.py   |  24 ++-
 src/iminuit/qtwidget.py | 430 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 525 insertions(+), 36 deletions(-)
 create mode 100644 src/iminuit/qtwidget.py

diff --git a/src/iminuit/cost.py b/src/iminuit/cost.py
index 76a75436..31e3235c 100644
--- a/src/iminuit/cost.py
+++ b/src/iminuit/cost.py
@@ -109,7 +109,11 @@ class documentation for details.
     TypeVar,
     Callable,
     cast,
+    TYPE_CHECKING,
 )
+if TYPE_CHECKING:
+    from matplotlib.axes import Axes
+    from matplotlib.figure import Figure
 import warnings
 from ._deprecated import deprecated_parameter
 
@@ -739,7 +743,10 @@ def __getitem__(self, key):
         return self._items.__getitem__(key)
 
     def visualize(
-        self, args: Sequence[float], component_kwargs: Dict[int, Dict[str, Any]] = None
+        self,
+        args: Sequence[float],
+        component_kwargs: Dict[int, Dict[str, Any]] = None,
+        fig: Figure = None,
     ):
         """
         Visualize data and model agreement (requires matplotlib).
@@ -757,16 +764,26 @@ def visualize(
             Dict that maps an index to dict of keyword arguments. This can be
             used to pass keyword arguments to a visualize method of a component with
             that index.
-        **kwargs :
-            Other keyword arguments are forwarded to all components.
+        fig : Figure, optional
+            The matplotlib figure into which the visualization is drawn.
+            If None is passed, the current figure is used. If the passed figure
+            has the same number of axes as there are components with a visualize
+            method, the axes are reused. Otherwise, new axes are created.
         """
-        from matplotlib import pyplot as plt
+        if fig is None:
+            from matplotlib import pyplot as plt
+            fig = plt.gcf()
 
         n = sum(hasattr(comp, "visualize") for comp in self)
 
-        fig = plt.gcf()
         fig.set_figwidth(n * fig.get_figwidth() / 1.5)
-        _, ax = plt.subplots(1, n, num=fig.number)
+        ax = fig.get_axes()
+        if len(ax) != n:
+            fig.clear()
+            _, ax = fig.subplots(1, n)
+            # For some reason fig.subplots does not return axes array but only
+            # a single axes even for n > 1
+            ax = fig.get_axes()
 
         if component_kwargs is None:
             component_kwargs = {}
@@ -776,8 +793,7 @@ def visualize(
             if not hasattr(comp, "visualize"):
                 continue
             kwargs = component_kwargs.get(k, {})
-            plt.sca(ax[i])
-            comp.visualize(cargs, **kwargs)
+            comp.visualize(cargs, ax=ax[i], **kwargs)
             i += 1
 
 
@@ -931,6 +947,7 @@ def visualize(
         args: Sequence[float],
         model_points: Union[int, Sequence[float]] = 0,
         bins: int = 50,
+        ax: Axes = None,
     ):
         """
         Visualize data and model agreement (requires matplotlib).
@@ -947,8 +964,13 @@ def visualize(
             it is interpreted as the point locations.
         bins : int, optional
             number of bins. Default is 50 bins.
+        ax : Axes, optional
+            The matplotlib axes into which the visualization is drawn.
+            If None is passed, the current axes is used.
         """
-        from matplotlib import pyplot as plt
+        if ax is None:
+            from matplotlib import pyplot as plt
+            ax = plt.gca()
 
         x = np.sort(self.data)
 
@@ -974,8 +996,8 @@ def visualize(
         cx = 0.5 * (xe[1:] + xe[:-1])
         dx = xe[1] - xe[0]
 
-        plt.errorbar(cx, n, n**0.5, fmt="ok")
-        plt.fill_between(xm, 0, ym * dx, fc="C0")
+        ax.errorbar(cx, n, n**0.5, fmt="ok")
+        ax.fill_between(xm, 0, ym * dx, fc="C0")
 
     def fisher_information(self, *args: float) -> NDArray:
         """
@@ -1375,7 +1397,7 @@ def prediction(
         """
         return self._pred(args)
 
-    def visualize(self, args: Sequence[float]) -> None:
+    def visualize(self, args: Sequence[float], ax: Axes = None) -> None:
         """
         Visualize data and model agreement (requires matplotlib).
 
@@ -1385,6 +1407,9 @@ def visualize(self, args: Sequence[float]) -> None:
         ----------
         args : sequence of float
             Parameter values.
+        ax : Axes, optional
+            The matplotlib axes into which the visualization is drawn.
+            If None is passed, the current axes is used.
 
         Notes
         -----
@@ -1394,10 +1419,12 @@ def visualize(self, args: Sequence[float]) -> None:
         comparison to a model, the visualization shows all data bins as a single
         sequence.
         """
-        return self._visualize(args)
+        return self._visualize(args, ax)
 
-    def _visualize(self, args: Sequence[float]) -> None:
-        from matplotlib import pyplot as plt
+    def _visualize(self, args: Sequence[float], ax: Axes) -> None:
+        if ax is None:
+            from matplotlib import pyplot as plt
+            ax = plt.gca()
 
         n, ne = self._n_err()
         mu = self.prediction(args)
@@ -1414,8 +1441,9 @@ def _visualize(self, args: Sequence[float]) -> None:
         else:
             xe = self.xe
             cx = 0.5 * (xe[1:] + xe[:-1])
-        plt.errorbar(cx, n, ne, fmt="ok")
-        plt.stairs(mu, xe, fill=True, color="C0")
+
+        ax.errorbar(cx, n, ne, fmt="ok")
+        ax.stairs(mu, xe, fill=True, color="C0")
 
     @abc.abstractmethod
     def _pred(
@@ -1858,8 +1886,10 @@ def prediction(self, args: Sequence[float]) -> Tuple[NDArray, NDArray]:
         mu, mu_var = self._pred(args)
         return mu, np.sqrt(mu_var)
 
-    def _visualize(self, args: Sequence[float]) -> None:
-        from matplotlib import pyplot as plt
+    def _visualize(self, args: Sequence[float], ax: Axes) -> None:
+        if ax is None:
+            from matplotlib import pyplot as plt
+            ax = plt.gca()
 
         n, ne = self._n_err()
         mu, mue = self.prediction(args)  # type: ignore
@@ -1876,11 +1906,11 @@ def _visualize(self, args: Sequence[float]) -> None:
             xe = self.xe
             cx = 0.5 * (xe[1:] + xe[:-1])
 
-        plt.errorbar(cx, n, ne, fmt="ok")
+        ax.errorbar(cx, n, ne, fmt="ok")
 
         # need fill=True and fill=False so that bins with mue=0 show up
         for fill in (False, True):
-            plt.stairs(mu + mue, xe, baseline=mu - mue, fill=fill, color="C0")
+            ax.stairs(mu + mue, xe, baseline=mu - mue, fill=fill, color="C0")
 
     def _pulls(self, args: Sequence[float]) -> NDArray:
         mu, mue = self.prediction(args)
@@ -2281,7 +2311,10 @@ def _ndata(self):
         return len(self._masked)
 
     def visualize(
-        self, args: ArrayLike, model_points: Union[int, Sequence[float]] = 0
+        self,
+        args: ArrayLike,
+        model_points: Union[int, Sequence[float]] = 0,
+        ax: Axes = None,
     ) -> Tuple[Tuple[NDArray, NDArray, NDArray], Tuple[NDArray, NDArray]]:
         """
         Visualize data and model agreement (requires matplotlib).
@@ -2297,14 +2330,19 @@ def visualize(
             How many points to use to draw the model. Default is 0, in this case
             an smart sampling algorithm selects the number of points. If array-like,
             it is interpreted as the point locations.
+        ax : Axes, optional
+            The matplotlib axes into which the visualization is drawn.
+            If None is passed, the current axes is used.
         """
-        from matplotlib import pyplot as plt
+        if ax is None:
+            from matplotlib import pyplot as plt
+            ax = plt.gca()
 
         if self._ndim > 1:
             raise ValueError("visualize is not implemented for multi-dimensional data")
 
         x, y, ye = self._masked.T
-        plt.errorbar(x, y, ye, fmt="ok")
+        ax.errorbar(x, y, ye, fmt="ok")
         if isinstance(model_points, Iterable):
             xm = np.array(model_points)
             ym = self.model(xm, *args)
@@ -2316,7 +2354,7 @@ def visualize(
             ym = self.model(xm, *args)
         else:
             xm, ym = _smart_sampling(lambda x: self.model(x, *args), x[0], x[-1])
-        plt.plot(xm, ym)
+        ax.plot(xm, ym)
         return (x, y, ye), (xm, ym)
 
     def prediction(self, args: Sequence[float]) -> NDArray:
@@ -2486,7 +2524,7 @@ def _has_grad(self) -> bool:
     def _ndata(self):
         return len(self._expected)
 
-    def visualize(self, args: ArrayLike):
+    def visualize(self, args: ArrayLike, ax: Axes = None):
         """
         Visualize data and model agreement (requires matplotlib).
 
@@ -2496,8 +2534,13 @@ def visualize(self, args: ArrayLike):
         ----------
         args : array-like
             Parameter values.
+        ax : Axes, optional
+            The matplotlib axes into which the visualization is drawn.
+            If None is passed, the current axes is used.
         """
-        from matplotlib import pyplot as plt
+        if ax is None:
+            from matplotlib import pyplot as plt
+            ax = plt.gca()
 
         args = np.atleast_1d(args)
 
@@ -2515,14 +2558,14 @@ def visualize(self, args: ArrayLike):
         for v, e, a in zip(val, err, args):
             pull = (a - v) / e
             max_pull = max(abs(pull), max_pull)
-            plt.errorbar(pull, -i, 0, 1, fmt="o", color="C0")
+            ax.errorbar(pull, -i, 0, 1, fmt="o", color="C0")
             i += 1
-        plt.axvline(0, color="k")
-        plt.xlim(-max_pull - 1.1, max_pull + 1.1)
-        yaxis = plt.gca().yaxis
+        ax.axvline(0, color="k")
+        ax.set_xlim(-max_pull - 1.1, max_pull + 1.1)
+        yaxis = ax.yaxis
         yaxis.set_ticks(-np.arange(n))
         yaxis.set_ticklabels(par)
-        plt.ylim(-n + 0.5, 0.5)
+        ax.set_ylim(-n + 0.5, 0.5)
 
 
 def _norm(value: ArrayLike) -> NDArray:
diff --git a/src/iminuit/minuit.py b/src/iminuit/minuit.py
index 63d6deca..76c2b1bb 100644
--- a/src/iminuit/minuit.py
+++ b/src/iminuit/minuit.py
@@ -2317,10 +2317,14 @@ def interactive(
         **kwargs,
     ):
         """
-        Return fitting widget (requires ipywidgets, IPython, matplotlib).
+        Interactive GUI for fitting.
 
-        A fitting widget is returned which can be displayed and manipulated in a
-        Jupyter notebook to find good starting parameters and to debug the fit.
+        Starts a fitting application (requires PyQt6, matplotlib) in which the
+        fit is visualized and the parameters can be manipulated to find good
+        starting parameters and to debug the fit.
+
+        When called in a Jupyter notebook (requires ipywidgets, IPython, matplotlib),
+        a fitting widget is returned instead, which can be displayed.
 
         Parameters
         ----------
@@ -2347,7 +2351,19 @@ def interactive(
         --------
         Minuit.visualize
         """
-        from iminuit.ipywidget import make_widget
+        try:
+            if (get_ipython().__class__.__name__ == "ZMQInteractiveShell"
+                    and "IPKernelApp" in get_ipython().config):
+                is_jupyter = True
+            else:
+                is_jupyter = False
+        except Exception:
+            is_jupyter = False
+
+        if is_jupyter:
+            from iminuit.ipywidget import make_widget
+        else:
+            from iminuit.qtwidget import make_widget
 
         plot = self._visualize(plot)
         return make_widget(self, plot, kwargs, raise_on_exception)
diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
new file mode 100644
index 00000000..3e875308
--- /dev/null
+++ b/src/iminuit/qtwidget.py
@@ -0,0 +1,430 @@
+"""Interactive fitting widget using PyQt6."""
+
+import warnings
+import numpy as np
+from typing import Dict, Any, Callable
+import sys
+from functools import partial
+import inspect
+
+try:
+    from PyQt6 import QtCore, QtGui, QtWidgets
+    from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg
+    from matplotlib import pyplot as plt
+except ModuleNotFoundError as e:
+    e.msg += (
+        "\n\nPlease install PyQt6, and matplotlib to enable interactive "
+        "outside of Jupyter notebooks."
+    )
+    raise
+
+
+def make_widget(
+    minuit: Any,
+    plot: Callable[..., None],
+    kwargs: Dict[str, Any],
+    raise_on_exception: bool,
+):
+    """Make interactive fitting widget."""
+    original_values = minuit.values[:]
+    original_limits = minuit.limits[:]
+
+    class FloatSlider(QtWidgets.QSlider):
+        # Qt sadly does not have a float slider, so we have to
+        # implement one ourselves.
+        floatValueChanged = QtCore.pyqtSignal(float)
+
+        def __init__(self, label):
+            super().__init__(QtCore.Qt.Orientation.Horizontal)
+            super().setMinimum(0)
+            super().setMaximum(int(1e8))
+            super().setValue(int(5e7))
+            self._min = 0.0
+            self._max = 1.0
+            self._value = 0.5
+            self._label = label
+            self.valueChanged.connect(self._emit_float_value_changed)
+
+        def _emit_float_value_changed(self, value=None):
+            if value is not None:
+                self._value = self._int_to_float(value)
+            self._label.setText(f"{self._value:.3g}")
+            self.floatValueChanged.emit(self._value)
+
+        def _int_to_float(self, value):
+            return self._min + (value / 1e8) * (self._max - self._min)
+
+        def _float_to_int(self, value):
+            return int((value - self._min) / (self._max - self._min) * 1e8)
+
+        def setMinimum(self, min_value):
+            if self._max <= min_value:
+                return
+            self._min = min_value
+            self.setValue(self._value)
+
+        def setMaximum(self, max_value):
+            if self._min >= max_value:
+                return
+            self._max = max_value
+            self.setValue(self._value)
+
+        def setValue(self, value):
+            if value < self._min:
+                self._value = self._min
+                super().setValue(0)
+                self._emit_float_value_changed()
+            elif value > self._max:
+                self._value = self._max
+                super().setValue(int(1e8))
+                self._emit_float_value_changed()
+            else:
+                self._value = value
+                self.blockSignals(True)
+                super().setValue(self._float_to_int(value))
+                self.blockSignals(False)
+
+        def value(self):
+            return self._value
+
+    class Parameter(QtWidgets.QGroupBox):
+        def __init__(self, minuit, par, callback):
+            super().__init__("")
+            self.par = par
+            self.callback = callback
+
+            size_policy = QtWidgets.QSizePolicy(
+                QtWidgets.QSizePolicy.Policy.MinimumExpanding,
+                QtWidgets.QSizePolicy.Policy.Fixed)
+            self.setSizePolicy(size_policy)
+            layout = QtWidgets.QVBoxLayout()
+            self.setLayout(layout)
+
+            label = QtWidgets.QLabel(
+                par, alignment=QtCore.Qt.AlignmentFlag.AlignCenter)
+            label.setMinimumSize(QtCore.QSize(50, 0))
+            self.value_label = QtWidgets.QLabel(
+                alignment=QtCore.Qt.AlignmentFlag.AlignCenter)
+            self.value_label.setMinimumSize(QtCore.QSize(50, 0))
+            self.slider = FloatSlider(self.value_label)
+            self.tmin = QtWidgets.QDoubleSpinBox(
+                alignment=QtCore.Qt.AlignmentFlag.AlignCenter)
+            self.tmin.setRange(_make_finite(-np.inf), _make_finite(np.inf))
+            self.tmax = QtWidgets.QDoubleSpinBox(
+                alignment=QtCore.Qt.AlignmentFlag.AlignCenter)
+            self.tmax.setRange(_make_finite(-np.inf), _make_finite(np.inf))
+            self.tmin.setSizePolicy(size_policy)
+            self.tmax.setSizePolicy(size_policy)
+            self.fix = QtWidgets.QPushButton("Fix")
+            self.fix.setCheckable(True)
+            self.fix.setChecked(minuit.fixed[par])
+            self.fit = QtWidgets.QPushButton("Fit")
+            self.fit.setCheckable(True)
+            self.fit.setChecked(False)
+            size_policy = QtWidgets.QSizePolicy(
+                QtWidgets.QSizePolicy.Policy.Fixed,
+                QtWidgets.QSizePolicy.Policy.Fixed)
+            self.fix.setSizePolicy(size_policy)
+            self.fit.setSizePolicy(size_policy)
+            layout1 = QtWidgets.QHBoxLayout()
+            layout.addLayout(layout1)
+            layout1.addWidget(label)
+            layout1.addWidget(self.slider)
+            layout1.addWidget(self.value_label)
+            layout1.addWidget(self.fix)
+            layout2 = QtWidgets.QHBoxLayout()
+            layout.addLayout(layout2)
+            layout2.addWidget(self.tmin)
+            layout2.addWidget(self.tmax)
+            layout2.addWidget(self.fit)
+
+            val = minuit.values[par]
+            vmin, vmax = minuit.limits[par]
+            self.step = _guess_initial_step(val, vmin, vmax)
+            vmin2 = vmin if np.isfinite(vmin) else val - 100 * self.step
+            vmax2 = vmax if np.isfinite(vmax) else val + 100 * self.step
+            self.tmin.setSingleStep(1e-1 * (vmax2 - vmin2))
+            self.tmax.setSingleStep(1e-1 * (vmax2 - vmin2))
+            self.tmin.setMinimum(_make_finite(vmin))
+            self.tmax.setMaximum(_make_finite(vmax))
+            self.reset(val, limits=(vmin, vmax))
+
+            self.slider.floatValueChanged.connect(self.on_val_change)
+            self.fix.clicked.connect(self.on_fix_toggled)
+            self.tmin.valueChanged.connect(self.on_min_change)
+            self.tmax.valueChanged.connect(self.on_max_change)
+            self.fit.clicked.connect(self.on_fit_toggled)
+
+        def on_val_change(self, val):
+            minuit.values[self.par] = val
+            self.callback()
+
+        def on_min_change(self):
+            tmin = self.tmin.value()
+            if tmin >= self.tmax.value():
+                self.tmin.blockSignals(True)
+                self.tmin.setValue(minuit.limits[self.par][0])
+                self.tmin.blockSignals(False)
+                return
+            self.slider.setMinimum(tmin)
+            lim = minuit.limits[self.par]
+            minuit.limits[self.par] = (tmin, lim[1])
+
+        def on_max_change(self):
+            tmax = self.tmax.value()
+            if tmax <= self.tmin.value():
+                self.tmax.blockSignals(True)
+                self.tmax.setValue(minuit.limits[self.par][1])
+                self.tmax.blockSignals(False)
+                return
+            self.slider.setMaximum(tmax)
+            lim = minuit.limits[self.par]
+            minuit.limits[self.par] = (lim[0], tmax)
+
+        def on_fix_toggled(self):
+            minuit.fixed[self.par] = self.fix.isChecked()
+            if self.fix.isChecked():
+                self.fit.setChecked(False)
+
+        def on_fit_toggled(self):
+            self.slider.setEnabled(not self.fit.isChecked())
+            if self.fit.isChecked():
+                self.fix.setChecked(False)
+                minuit.fixed[self.par] = False
+            self.callback()
+
+        def reset(self, val, limits=None):
+            # Set limits first so that the value won't be changed by the
+            # FloatSlider
+            if limits is not None:
+                vmin, vmax = limits
+                vmin = vmin if np.isfinite(vmin) else val - 100 * self.step
+                vmax = vmax if np.isfinite(vmax) else val + 100 * self.step
+                self.slider.blockSignals(True)
+                self.slider.setMinimum(vmin)
+                self.slider.blockSignals(True)
+                self.slider.setMaximum(vmax)
+                self.tmin.blockSignals(True)
+                self.tmin.setValue(vmin)
+                self.tmin.blockSignals(False)
+                self.tmax.blockSignals(True)
+                self.tmax.setValue(vmax)
+                self.tmax.blockSignals(False)
+
+            self.slider.blockSignals(True)
+            self.slider.setValue(val)
+            self.value_label.setText(f"{val:.3g}")
+            self.slider.blockSignals(False)
+
+    class MainWindow(QtWidgets.QMainWindow):
+        def __init__(self):
+            super().__init__()
+            self.resize(1200, 600)
+            font = QtGui.QFont()
+            font.setPointSize(12)
+            self.setFont(font)
+            centralwidget = QtWidgets.QWidget(parent=self)
+            self.setCentralWidget(centralwidget)
+            central_layout = QtWidgets.QVBoxLayout(centralwidget)
+            tab = QtWidgets.QTabWidget(parent=centralwidget)
+            interactive_tab = QtWidgets.QWidget()
+            tab.addTab(interactive_tab, "Interactive")
+            results_tab = QtWidgets.QWidget()
+            tab.addTab(results_tab, "Results")
+            central_layout.addWidget(tab)
+
+            interactive_layout = QtWidgets.QGridLayout(interactive_tab)
+
+            plot_group = QtWidgets.QGroupBox("", parent=interactive_tab)
+            size_policy = QtWidgets.QSizePolicy(
+                QtWidgets.QSizePolicy.Policy.MinimumExpanding,
+                QtWidgets.QSizePolicy.Policy.MinimumExpanding)
+            plot_group.setSizePolicy(size_policy)
+            plot_layout = QtWidgets.QVBoxLayout(plot_group)
+            # Use pyplot here to allow users to use pyplot in the plot
+            # function (not recommended / unstable)
+            self.fig, ax = plt.subplots()
+            self.canvas = FigureCanvasQTAgg(self.fig)
+            plot_layout.addWidget(self.canvas)
+            plot_layout.addStretch()
+            interactive_layout.addWidget(plot_group, 0, 0, 2, 1)
+            try:
+                plot(minuit.values, fig=self.fig)
+                kwargs["fig"] = self.fig
+            except Exception:
+                pass
+            try:
+                plot(minuit.values, ax=ax)
+                kwargs["ax"] = ax
+            except Exception:
+                pass
+            self.fig_width = self.fig.get_figwidth()
+
+            button_group = QtWidgets.QGroupBox("", parent=interactive_tab)
+            size_policy = QtWidgets.QSizePolicy(
+                QtWidgets.QSizePolicy.Policy.Expanding,
+                QtWidgets.QSizePolicy.Policy.Fixed)
+            button_group.setSizePolicy(size_policy)
+            button_layout = QtWidgets.QHBoxLayout(button_group)
+            self.fit_button = QtWidgets.QPushButton("Fit", parent=button_group)
+            self.fit_button.setStyleSheet(
+                "background-color: #2196F3; color: white")
+            self.fit_button.clicked.connect(partial(self.do_fit, plot=True))
+            button_layout.addWidget(self.fit_button)
+            self.update_button = QtWidgets.QPushButton(
+                "Continuous", parent=button_group)
+            self.update_button.setCheckable(True)
+            self.update_button.setChecked(True)
+            self.update_button.clicked.connect(self.on_update_button_clicked)
+            button_layout.addWidget(self.update_button)
+            self.reset_button = QtWidgets.QPushButton(
+                "Reset", parent=button_group)
+            self.reset_button.setStyleSheet(
+                "background-color: #F44336; color: white")
+            self.reset_button.clicked.connect(self.on_reset_button_clicked)
+            button_layout.addWidget(self.reset_button)
+            self.algo_choice = QtWidgets.QComboBox(parent=button_group)
+            self.algo_choice.setStyleSheet("QComboBox { text-align: center; }")
+            self.algo_choice.addItems(["Migrad", "Scipy", "Simplex"])
+            button_layout.addWidget(self.algo_choice)
+            interactive_layout.addWidget(button_group, 0, 1, 1, 1)
+
+            scroll_area = QtWidgets.QScrollArea()
+            scroll_area.setWidgetResizable(True)
+            size_policy = QtWidgets.QSizePolicy(
+                QtWidgets.QSizePolicy.Policy.MinimumExpanding,
+                QtWidgets.QSizePolicy.Policy.MinimumExpanding)
+            scroll_area.setSizePolicy(size_policy)
+            scroll_area_contents = QtWidgets.QWidget()
+            parameter_layout = QtWidgets.QVBoxLayout(scroll_area_contents)
+            scroll_area.setWidget(scroll_area_contents)
+            interactive_layout.addWidget(scroll_area, 1, 1, 1, 1)
+            self.parameters = []
+            for par in minuit.parameters:
+                parameter = Parameter(minuit, par, self.on_parameter_change)
+                self.parameters.append(parameter)
+                parameter_layout.addWidget(parameter)
+            parameter_layout.addStretch()
+
+            results_layout = QtWidgets.QVBoxLayout(results_tab)
+            self.results_text = QtWidgets.QTextEdit(parent=results_tab)
+            self.results_text.setReadOnly(True)
+            results_layout.addWidget(self.results_text)
+
+            self.plot_with_frame(from_fit=False, report_success=False)
+
+        def plot_with_frame(self, from_fit, report_success):
+            self.fig.set_figwidth(self.fig_width)
+            try:
+                with warnings.catch_warnings():
+                    minuit.visualize(plot, **kwargs)
+            except Exception:
+                if raise_on_exception:
+                    raise
+
+                import traceback
+
+                self.fig.figtext(
+                    0,
+                    0.5,
+                    traceback.format_exc(limit=-1),
+                    fontdict={"family": "monospace", "size": "x-small"},
+                    va="center",
+                    color="r",
+                    backgroundcolor="w",
+                    wrap=True,
+                )
+                return
+
+            fval = minuit.fmin.fval if from_fit else minuit._fcn(minuit.values)
+            self.fig.get_axes()[0].text(
+                0.05,
+                1.05,
+                f"FCN = {fval:.3f}",
+                transform=self.fig.get_axes()[0].transAxes,
+                fontsize="x-large",
+            )
+            if from_fit and report_success:
+                self.fig.get_axes()[-1].text(
+                    0.95,
+                    1.05,
+                    f"{'success' if minuit.valid and minuit.accurate else 'FAILURE'}",
+                    transform=self.fig.get_axes()[-1].transAxes,
+                    fontsize="x-large",
+                    ha="right",
+                )
+
+        def fit(self):
+            if self.algo_choice.currentText() == "Migrad":
+                minuit.migrad()
+            elif self.algo_choice.currentText() == "Scipy":
+                minuit.scipy()
+            elif self.algo_choice.currentText() == "Simplex":
+                minuit.simplex()
+                return False
+            else:
+                assert False  # pragma: no cover, should never happen
+            return True
+
+        def on_parameter_change(self, from_fit=False,
+                                report_success=False):
+            if not from_fit:
+                if any(x.fit.isChecked() for x in self.parameters):
+                    saved = minuit.fixed[:]
+                    for i, x in enumerate(self.parameters):
+                        minuit.fixed[i] = not x.fit.isChecked()
+                    from_fit = True
+                    report_success = self.do_fit(plot=False)
+                    self.results_text.clear()
+                    self.results_text.setHtml(minuit._repr_html_())
+                    minuit.fixed = saved
+            else:
+                self.results_text.clear()
+                self.results_text.setHtml(minuit._repr_html_())
+
+            for ax in self.fig.get_axes():
+                ax.clear()
+            self.plot_with_frame(from_fit, report_success)
+            self.canvas.draw_idle()
+
+        def do_fit(self, plot=True):
+            report_success = self.fit()
+            for i, x in enumerate(self.parameters):
+                x.reset(val=minuit.values[i])
+            if not plot:
+                return report_success
+            self.on_parameter_change(
+                from_fit=True, report_success=report_success)
+
+        def on_update_button_clicked(self):
+            for x in self.parameters:
+                x.slider.setTracking(self.update_button.isChecked())
+
+        def on_reset_button_clicked(self):
+            minuit.reset()
+            minuit.values = original_values
+            minuit.limits = original_limits
+            for i, x in enumerate(self.parameters):
+                x.reset(val=minuit.values[i], limits=original_limits[i])
+            self.on_parameter_change()
+
+    # Set up the Qt application
+    app = QtWidgets.QApplication.instance()
+    if app is None:
+        app = QtWidgets.QApplication([])
+    main_window = MainWindow()
+    main_window.show()
+    app.exec()
+
+
+def _make_finite(x: float) -> float:
+    sign = -1 if x < 0 else 1
+    if abs(x) == np.inf:
+        return sign * sys.float_info.max
+    return x
+
+
+def _guess_initial_step(val: float, vmin: float, vmax: float) -> float:
+    if np.isfinite(vmin) and np.isfinite(vmax):
+        return 1e-2 * (vmax - vmin)
+    return 1e-2

From 59c3bf89c86cae5a8d69284c782b52e4b1f765d0 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Tue, 29 Oct 2024 06:13:56 +0100
Subject: [PATCH 02/49] Added PyQt6 optional dependency

---
 pyproject.toml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/pyproject.toml b/pyproject.toml
index 7b8aa6d9..ad8940da 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -44,6 +44,7 @@ test = [
     "ipywidgets",
     # needed by ipywidgets >= 8.0.6
     "ipykernel",
+    "PyQt6",
     "joblib",
     "jacobi",
     "matplotlib",
@@ -52,6 +53,7 @@ test = [
     "numba-stats; platform_python_implementation=='CPython'",
     "pytest",
     "pytest-xdist",
+    "pytest-qt",
     "scipy",
     "tabulate",
     "boost_histogram",

From 51bbf1faadbf5e003432983d7c3ce05f488bdf9c Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Tue, 29 Oct 2024 06:14:47 +0100
Subject: [PATCH 03/49] Added tests

---
 src/iminuit/minuit.py            |  14 +-
 src/iminuit/qtwidget.py          |   9 +-
 tests/test_draw.py               | 221 ++++++++++++++++++++++++++-----
 tests/test_without_ipywidgets.py |  16 ++-
 tests/test_without_pyqt6.py      |  22 +++
 5 files changed, 234 insertions(+), 48 deletions(-)
 create mode 100644 tests/test_without_pyqt6.py

diff --git a/src/iminuit/minuit.py b/src/iminuit/minuit.py
index 76c2b1bb..e66c8d57 100644
--- a/src/iminuit/minuit.py
+++ b/src/iminuit/minuit.py
@@ -2314,6 +2314,7 @@ def interactive(
         self,
         plot: Callable = None,
         raise_on_exception=False,
+        qt_exec=True,
         **kwargs,
     ):
         """
@@ -2321,7 +2322,8 @@ def interactive(
 
         Starts a fitting application (requires PyQt6, matplotlib) in which the
         fit is visualized and the parameters can be manipulated to find good
-        starting parameters and to debug the fit.
+        starting parameters and to debug the fit. The QApplication is executed
+        by default, but can be disabled by setting qt_exec=False.
 
         When called in a Jupyter notebook (requires ipywidgets, IPython, matplotlib),
         a fitting widget is returned instead, which can be displayed.
@@ -2339,6 +2341,8 @@ def interactive(
             The default is to catch exceptions in the plot function and convert them
             into a plotted message. In unit tests, raise_on_exception should be set to
             True to allow detecting errors.
+        qt_exec : bool, optional
+            Whether the PyQt6 application is executed. This is ignored in Jupyter notebooks.
         **kwargs :
             Any other keyword arguments are forwarded to the plot function.
 
@@ -2352,6 +2356,7 @@ def interactive(
         Minuit.visualize
         """
         try:
+            from IPython import get_ipython
             if (get_ipython().__class__.__name__ == "ZMQInteractiveShell"
                     and "IPKernelApp" in get_ipython().config):
                 is_jupyter = True
@@ -2360,13 +2365,14 @@ def interactive(
         except Exception:
             is_jupyter = False
 
+        plot = self._visualize(plot)
+
         if is_jupyter:
             from iminuit.ipywidget import make_widget
+            return make_widget(self, plot, kwargs, raise_on_exception)
         else:
             from iminuit.qtwidget import make_widget
-
-        plot = self._visualize(plot)
-        return make_widget(self, plot, kwargs, raise_on_exception)
+            return make_widget(self, plot, kwargs, raise_on_exception, qt_exec)
 
     def _free_parameters(self) -> Set[str]:
         return set(mp.name for mp in self._last_state if not mp.is_fixed)
diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 3e875308..cafca11a 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -5,7 +5,6 @@
 from typing import Dict, Any, Callable
 import sys
 from functools import partial
-import inspect
 
 try:
     from PyQt6 import QtCore, QtGui, QtWidgets
@@ -24,6 +23,7 @@ def make_widget(
     plot: Callable[..., None],
     kwargs: Dict[str, Any],
     raise_on_exception: bool,
+    qt_exec: bool,
 ):
     """Make interactive fitting widget."""
     original_values = minuit.values[:]
@@ -324,7 +324,7 @@ def plot_with_frame(self, from_fit, report_success):
 
                 import traceback
 
-                self.fig.figtext(
+                self.fig.text(
                     0,
                     0.5,
                     traceback.format_exc(limit=-1),
@@ -414,7 +414,10 @@ def on_reset_button_clicked(self):
         app = QtWidgets.QApplication([])
     main_window = MainWindow()
     main_window.show()
-    app.exec()
+
+    if qt_exec:
+        app.exec()
+    return app, main_window
 
 
 def _make_finite(x: float) -> float:
diff --git a/tests/test_draw.py b/tests/test_draw.py
index b4e9e088..916449b5 100644
--- a/tests/test_draw.py
+++ b/tests/test_draw.py
@@ -4,6 +4,7 @@
 import numpy as np
 from numpy.testing import assert_allclose
 import contextlib
+from unittest.mock import patch, MagicMock
 
 mpl = pytest.importorskip("matplotlib")
 plt = pytest.importorskip("matplotlib.pyplot")
@@ -136,7 +137,7 @@ def test_mnmatrix_7(fig):
 
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive():
+def test_interactive_ipywidgets():
     ipywidgets = pytest.importorskip("ipywidgets")
 
     def cost(a, b):
@@ -161,40 +162,137 @@ def assert_call(self):
     plot = Plot()
 
     m = Minuit(cost, 1, 1)
+
+    with patch("IPython.get_ipython") as mock_get_ipython:
+        mock_shell = MagicMock()
+        mock_shell.__class__.__name__ = "ZMQInteractiveShell"
+        mock_shell.config = {"IPKernelApp": True}
+        mock_get_ipython.return_value = mock_shell
+
+        with pytest.raises(AttributeError, match="no visualize method"):
+            m.interactive(raise_on_exception=True)
+
+        with plot.assert_call():
+            out1 = m.interactive(plot)
+        assert isinstance(out1, ipywidgets.HBox)
+
+        # manipulate state to also check this code
+        ui = out1.children[1]
+        header, parameters = ui.children
+        fit_button, update_button, reset_button, algo_select = header.children
+        with plot.assert_call():
+            fit_button.click()
+        assert_allclose(m.values, (0, 0), atol=1e-5)
+        with plot.assert_call():
+            reset_button.click()
+        assert_allclose(m.values, (1, 1), atol=1e-5)
+
+        algo_select.value = "Scipy"
+        with plot.assert_call():
+            fit_button.click()
+
+        algo_select.value = "Simplex"
+        with plot.assert_call():
+            fit_button.click()
+
+        update_button.value = False
+        with plot.assert_call():
+            # because of implementation details, we have to trigger the slider several times
+            for i in range(5):
+                parameters.children[0].slider.value = i  # change first slider
+        parameters.children[0].fix.value = True
+        with plot.assert_call():
+            parameters.children[0].fit.value = True
+
+        class Cost:
+            def visualize(self, args):
+                return plot(args)
+
+            def __call__(self, a, b):
+                return (a - 100) ** 2 + (b + 100) ** 2
+
+        c = Cost()
+        m = Minuit(c, 0, 0)
+        with plot.assert_call():
+            out = m.interactive(raise_on_exception=True)
+
+        # this should modify slider range
+        ui = out.children[1]
+        header, parameters = ui.children
+        fit_button, update_button, reset_button, algo_select = header.children
+        assert parameters.children[0].slider.max == 1
+        assert parameters.children[1].slider.min == -1
+        with plot.assert_call():
+            fit_button.click()
+        assert_allclose(m.values, (100, -100), atol=1e-5)
+        # this should trigger an exception
+        plot.raises = True
+        with plot.assert_call():
+            fit_button.click()
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_interactive_pyqt6(qtbot):
+    PyQt6 = pytest.importorskip("PyQt6")
+
+    def cost(a, b):
+        return a**2 + b**2
+
+    class Plot:
+        def __init__(self):
+            self.called = False
+            self.raises = False
+
+        def __call__(self, args):
+            self.called = True
+            if self.raises:
+                raise ValueError("foo")
+
+        @contextlib.contextmanager
+        def assert_call(self):
+            self.called = False
+            yield
+            assert self.called
+
+    plot = Plot()
+
+    m = Minuit(cost, 1, 1)
+
     with pytest.raises(AttributeError, match="no visualize method"):
-        m.interactive(raise_on_exception=True)
+        mw = m.interactive(raise_on_exception=True, qt_exec=False)[1]
+        qtbot.addWidget(mw)
+        mw.close()
+        mw.deleteLater()
 
     with plot.assert_call():
-        out1 = m.interactive(plot)
-    assert isinstance(out1, ipywidgets.HBox)
+        mw1 = m.interactive(plot, qt_exec=False)[1]
+    qtbot.addWidget(mw1)
+    assert isinstance(mw1, PyQt6.QtWidgets.QMainWindow)
 
     # manipulate state to also check this code
-    ui = out1.children[1]
-    header, parameters = ui.children
-    fit_button, update_button, reset_button, algo_select = header.children
     with plot.assert_call():
-        fit_button.click()
+        mw1.fit_button.click()
     assert_allclose(m.values, (0, 0), atol=1e-5)
     with plot.assert_call():
-        reset_button.click()
+        mw1.reset_button.click()
     assert_allclose(m.values, (1, 1), atol=1e-5)
 
-    algo_select.value = "Scipy"
+    mw1.algo_choice.setCurrentText("Scipy")
     with plot.assert_call():
-        fit_button.click()
+        mw1.fit_button.click()
 
-    algo_select.value = "Simplex"
+    mw1.algo_choice.setCurrentText("Simplex")
     with plot.assert_call():
-        fit_button.click()
+        mw1.fit_button.click()
 
-    update_button.value = False
+    mw1.update_button.click()
     with plot.assert_call():
-        # because of implementation details, we have to trigger the slider several times
-        for i in range(5):
-            parameters.children[0].slider.value = i  # change first slider
-    parameters.children[0].fix.value = True
+        mw1.parameters[0].slider.valueChanged.emit(int(5e7))
+    mw1.parameters[0].fix.click()
     with plot.assert_call():
-        parameters.children[0].fit.value = True
+        mw1.parameters[0].fit.click()
+
+    mw1.close()
+    mw1.deleteLater()
 
     class Cost:
         def visualize(self, args):
@@ -206,25 +304,24 @@ def __call__(self, a, b):
     c = Cost()
     m = Minuit(c, 0, 0)
     with plot.assert_call():
-        out = m.interactive(raise_on_exception=True)
+        mw = m.interactive(raise_on_exception=True, qt_exec=False)[1]
+    qtbot.addWidget(mw)
 
     # this should modify slider range
-    ui = out.children[1]
-    header, parameters = ui.children
-    fit_button, update_button, reset_button, algo_select = header.children
-    assert parameters.children[0].slider.max == 1
-    assert parameters.children[1].slider.min == -1
+    assert mw.parameters[0].slider._max == 1
+    assert mw.parameters[1].slider._min == -1
     with plot.assert_call():
-        fit_button.click()
+        mw.fit_button.click()
     assert_allclose(m.values, (100, -100), atol=1e-5)
     # this should trigger an exception
-    plot.raises = True
-    with plot.assert_call():
-        fit_button.click()
-
+    #plot.raises = True
+    #with plot.assert_call():
+    #    mw.fit_button.click()
+    mw.close()
+    mw.deleteLater()
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_raises():
+def test_interactive_ipywidgets_raises():
     pytest.importorskip("ipywidgets")
 
     def raiser(args):
@@ -233,14 +330,40 @@ def raiser(args):
     m = Minuit(lambda x, y: 0, 0, 1)
 
     # by default do not raise
-    m.interactive(raiser)
+    with patch("IPython.get_ipython") as mock_get_ipython:
+        mock_shell = MagicMock()
+        mock_shell.__class__.__name__ = "ZMQInteractiveShell"
+        mock_shell.config = {"IPKernelApp": True}
+        mock_get_ipython.return_value = mock_shell
 
-    with pytest.raises(ValueError):
-        m.interactive(raiser, raise_on_exception=True)
+        m.interactive(raiser)
 
+        with pytest.raises(ValueError):
+            m.interactive(raiser, raise_on_exception=True)
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_with_array_func():
+def test_interactive_pyqt6_raises(qtbot):
+    pytest.importorskip("PyQt6")
+
+    def raiser(args):
+        raise ValueError
+
+    m = Minuit(lambda x, y: 0, 0, 1)
+
+    # by default do not raise
+    mw = m.interactive(raiser, qt_exec=False)[1]
+    qtbot.addWidget(mw)
+    mw.close()
+    mw.deleteLater()
+
+    with pytest.raises(ValueError):
+        mw = m.interactive(raiser, raise_on_exception=True, qt_exec=False)[1]
+        qtbot.addWidget(mw)
+        mw.close()
+        mw.deleteLater()
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_interactive_ipywidgets_with_array_func():
     pytest.importorskip("ipywidgets")
 
     def cost(par):
@@ -254,5 +377,31 @@ def __call__(self, par):
 
     trace_args = TraceArgs()
     m = Minuit(cost, (1, 2))
-    m.interactive(trace_args)
+
+    with patch("IPython.get_ipython") as mock_get_ipython:
+        mock_shell = MagicMock()
+        mock_shell.__class__.__name__ = "ZMQInteractiveShell"
+        mock_shell.config = {"IPKernelApp": True}
+        mock_get_ipython.return_value = mock_shell
+
+        m.interactive(trace_args)
+        assert trace_args.nargs > 0
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_interactive_pyqt6_with_array_func(qtbot):
+    pytest.importorskip("PyQt6")
+
+    def cost(par):
+        return par[0] ** 2 + (par[1] / 2) ** 2
+
+    class TraceArgs:
+        nargs = 0
+
+        def __call__(self, par):
+            self.nargs = len(par)
+
+    trace_args = TraceArgs()
+    m = Minuit(cost, (1, 2))
+
+    qtbot.addWidget(m.interactive(trace_args, qt_exec=False)[1])
     assert trace_args.nargs > 0
diff --git a/tests/test_without_ipywidgets.py b/tests/test_without_ipywidgets.py
index fbd9b508..54365db0 100644
--- a/tests/test_without_ipywidgets.py
+++ b/tests/test_without_ipywidgets.py
@@ -1,18 +1,24 @@
 from iminuit._hide_modules import hide_modules
 from iminuit.cost import LeastSquares
 import pytest
+from unittest.mock import patch, MagicMock
 
 pytest.importorskip("ipywidgets")
 
-
 def test_interactive():
     pytest.importorskip("matplotlib")
     import iminuit
 
     cost = LeastSquares([1.1, 2.2], [3.3, 4.4], 1, lambda x, a: a * x)
 
-    iminuit.Minuit(cost, 1).interactive()
+    with patch("IPython.get_ipython") as mock_get_ipython:
+        mock_shell = MagicMock()
+        mock_shell.__class__.__name__ = "ZMQInteractiveShell"
+        mock_shell.config = {"IPKernelApp": True}
+        mock_get_ipython.return_value = mock_shell
+
+        iminuit.Minuit(cost, 1).interactive()
 
-    with hide_modules("ipywidgets", reload="iminuit.ipywidget"):
-        with pytest.raises(ModuleNotFoundError, match="Please install"):
-            iminuit.Minuit(cost, 1).interactive()
+        with hide_modules("ipywidgets", reload="iminuit.ipywidget"):
+            with pytest.raises(ModuleNotFoundError, match="Please install"):
+                iminuit.Minuit(cost, 1).interactive()
diff --git a/tests/test_without_pyqt6.py b/tests/test_without_pyqt6.py
new file mode 100644
index 00000000..0bc59486
--- /dev/null
+++ b/tests/test_without_pyqt6.py
@@ -0,0 +1,22 @@
+from iminuit._hide_modules import hide_modules
+from iminuit.cost import LeastSquares
+import pytest
+
+pytest.importorskip("PyQt6")
+
+def test_interactive(qtbot):
+    pytest.importorskip("matplotlib")
+    import iminuit
+
+    cost = LeastSquares([1.1, 2.2], [3.3, 4.4], 1, lambda x, a: a * x)
+    mw = iminuit.Minuit(cost, 1).interactive(qt_exec=False)[1]
+    qtbot.addWidget(mw)
+    mw.close()
+    mw.deleteLater()
+
+    with hide_modules("PyQt6", reload="iminuit.qtwidget"):
+        with pytest.raises(ModuleNotFoundError, match="Please install"):
+            mw = iminuit.Minuit(cost, 1).interactive(qt_exec=False)[1]
+            qtbot.addWidget(mw)
+            mw.close()
+            mw.deleteLater()

From 1367a880b589a5044c89e2a5415b20e347ac301d Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Fri, 1 Nov 2024 19:24:30 +0100
Subject: [PATCH 04/49] Bug fixes

---
 src/iminuit/minuit.py   |   1 -
 src/iminuit/qtwidget.py | 185 +++++++++++++++++-----------------------
 2 files changed, 80 insertions(+), 106 deletions(-)

diff --git a/src/iminuit/minuit.py b/src/iminuit/minuit.py
index e66c8d57..3c81f2ee 100644
--- a/src/iminuit/minuit.py
+++ b/src/iminuit/minuit.py
@@ -2356,7 +2356,6 @@ def interactive(
         Minuit.visualize
         """
         try:
-            from IPython import get_ipython
             if (get_ipython().__class__.__name__ == "ZMQInteractiveShell"
                     and "IPKernelApp" in get_ipython().config):
                 is_jupyter = True
diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index cafca11a..4c188556 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -29,64 +29,6 @@ def make_widget(
     original_values = minuit.values[:]
     original_limits = minuit.limits[:]
 
-    class FloatSlider(QtWidgets.QSlider):
-        # Qt sadly does not have a float slider, so we have to
-        # implement one ourselves.
-        floatValueChanged = QtCore.pyqtSignal(float)
-
-        def __init__(self, label):
-            super().__init__(QtCore.Qt.Orientation.Horizontal)
-            super().setMinimum(0)
-            super().setMaximum(int(1e8))
-            super().setValue(int(5e7))
-            self._min = 0.0
-            self._max = 1.0
-            self._value = 0.5
-            self._label = label
-            self.valueChanged.connect(self._emit_float_value_changed)
-
-        def _emit_float_value_changed(self, value=None):
-            if value is not None:
-                self._value = self._int_to_float(value)
-            self._label.setText(f"{self._value:.3g}")
-            self.floatValueChanged.emit(self._value)
-
-        def _int_to_float(self, value):
-            return self._min + (value / 1e8) * (self._max - self._min)
-
-        def _float_to_int(self, value):
-            return int((value - self._min) / (self._max - self._min) * 1e8)
-
-        def setMinimum(self, min_value):
-            if self._max <= min_value:
-                return
-            self._min = min_value
-            self.setValue(self._value)
-
-        def setMaximum(self, max_value):
-            if self._min >= max_value:
-                return
-            self._max = max_value
-            self.setValue(self._value)
-
-        def setValue(self, value):
-            if value < self._min:
-                self._value = self._min
-                super().setValue(0)
-                self._emit_float_value_changed()
-            elif value > self._max:
-                self._value = self._max
-                super().setValue(int(1e8))
-                self._emit_float_value_changed()
-            else:
-                self._value = value
-                self.blockSignals(True)
-                super().setValue(self._float_to_int(value))
-                self.blockSignals(False)
-
-        def value(self):
-            return self._value
-
     class Parameter(QtWidgets.QGroupBox):
         def __init__(self, minuit, par, callback):
             super().__init__("")
@@ -106,7 +48,9 @@ def __init__(self, minuit, par, callback):
             self.value_label = QtWidgets.QLabel(
                 alignment=QtCore.Qt.AlignmentFlag.AlignCenter)
             self.value_label.setMinimumSize(QtCore.QSize(50, 0))
-            self.slider = FloatSlider(self.value_label)
+            self.slider = QtWidgets.QSlider(QtCore.Qt.Orientation.Horizontal)
+            self.slider.setMinimum(0)
+            self.slider.setMaximum(int(1e8))
             self.tmin = QtWidgets.QDoubleSpinBox(
                 alignment=QtCore.Qt.AlignmentFlag.AlignCenter)
             self.tmin.setRange(_make_finite(-np.inf), _make_finite(np.inf))
@@ -138,46 +82,70 @@ def __init__(self, minuit, par, callback):
             layout2.addWidget(self.tmax)
             layout2.addWidget(self.fit)
 
-            val = minuit.values[par]
-            vmin, vmax = minuit.limits[par]
-            self.step = _guess_initial_step(val, vmin, vmax)
-            vmin2 = vmin if np.isfinite(vmin) else val - 100 * self.step
-            vmax2 = vmax if np.isfinite(vmax) else val + 100 * self.step
-            self.tmin.setSingleStep(1e-1 * (vmax2 - vmin2))
-            self.tmax.setSingleStep(1e-1 * (vmax2 - vmin2))
-            self.tmin.setMinimum(_make_finite(vmin))
-            self.tmax.setMaximum(_make_finite(vmax))
-            self.reset(val, limits=(vmin, vmax))
-
-            self.slider.floatValueChanged.connect(self.on_val_change)
+            self.reset(minuit.values[par], limits=minuit.limits[par])
+
+            self.tmin.setSingleStep(1e-1 * (self.vmax - self.vmin))
+            self.tmax.setSingleStep(1e-1 * (self.vmax - self.vmin))
+            self.tmin.setMinimum(_make_finite(minuit.limits[par][0]))
+            self.tmax.setMaximum(_make_finite(minuit.limits[par][1]))
+
+            self.slider.valueChanged.connect(self.on_val_changed)
             self.fix.clicked.connect(self.on_fix_toggled)
-            self.tmin.valueChanged.connect(self.on_min_change)
-            self.tmax.valueChanged.connect(self.on_max_change)
+            self.tmin.valueChanged.connect(self.on_min_changed)
+            self.tmax.valueChanged.connect(self.on_max_changed)
             self.fit.clicked.connect(self.on_fit_toggled)
 
-        def on_val_change(self, val):
+        def _int_to_float(self, value):
+            return self.vmin + (value / 1e8) * (self.vmax - self.vmin)
+
+        def _float_to_int(self, value):
+            return int((value - self.vmin) / (self.vmax - self.vmin) * 1e8)
+
+        def on_val_changed(self, val):
+            val = self._int_to_float(val)
+            self.value_label.setText(f"{val:.3g}")
             minuit.values[self.par] = val
             self.callback()
 
-        def on_min_change(self):
+        def on_min_changed(self):
             tmin = self.tmin.value()
-            if tmin >= self.tmax.value():
+            if tmin >= self.vmax:
                 self.tmin.blockSignals(True)
-                self.tmin.setValue(minuit.limits[self.par][0])
+                self.tmin.setValue(self.vmin)
                 self.tmin.blockSignals(False)
                 return
-            self.slider.setMinimum(tmin)
+            self.vmin = tmin
+            self.slider.blockSignals(True)
+            if tmin > self.val:
+                self.val = tmin
+                minuit.values[self.par] = tmin
+                self.slider.setValue(0)
+                self.value_label.setText(f"{self.val:.3g}")
+                self.callback()
+            else:
+                self.slider.setValue(self._float_to_int(self.val))
+            self.slider.blockSignals(False)
             lim = minuit.limits[self.par]
             minuit.limits[self.par] = (tmin, lim[1])
 
-        def on_max_change(self):
+        def on_max_changed(self):
             tmax = self.tmax.value()
             if tmax <= self.tmin.value():
                 self.tmax.blockSignals(True)
-                self.tmax.setValue(minuit.limits[self.par][1])
+                self.tmax.setValue(self.vmax)
                 self.tmax.blockSignals(False)
                 return
-            self.slider.setMaximum(tmax)
+            self.vmax = tmax
+            self.slider.blockSignals(True)
+            if tmax < self.val:
+                self.val = tmax
+                minuit.values[self.par] = tmax
+                self.slider.setValue(int(1e8))
+                self.value_label.setText(f"{self.val:.3g}")
+                self.callback()
+            else:
+                self.slider.setValue(self._float_to_int(self.val))
+            self.slider.blockSignals(False)
             lim = minuit.limits[self.par]
             minuit.limits[self.par] = (lim[0], tmax)
 
@@ -190,31 +158,37 @@ def on_fit_toggled(self):
             self.slider.setEnabled(not self.fit.isChecked())
             if self.fit.isChecked():
                 self.fix.setChecked(False)
-                minuit.fixed[self.par] = False
             self.callback()
 
         def reset(self, val, limits=None):
-            # Set limits first so that the value won't be changed by the
-            # FloatSlider
             if limits is not None:
                 vmin, vmax = limits
-                vmin = vmin if np.isfinite(vmin) else val - 100 * self.step
-                vmax = vmax if np.isfinite(vmax) else val + 100 * self.step
-                self.slider.blockSignals(True)
-                self.slider.setMinimum(vmin)
-                self.slider.blockSignals(True)
-                self.slider.setMaximum(vmax)
+                step = _guess_initial_step(val, vmin, vmax)
+                self.vmin = vmin if np.isfinite(vmin) else val - 100 * step
+                self.vmax = vmax if np.isfinite(vmax) else val + 100 * step
                 self.tmin.blockSignals(True)
-                self.tmin.setValue(vmin)
+                self.tmin.setValue(self.vmin)
                 self.tmin.blockSignals(False)
                 self.tmax.blockSignals(True)
-                self.tmax.setValue(vmax)
+                self.tmax.setValue(self.vmax)
+                self.tmax.blockSignals(False)
+
+            self.val = val
+            if self.val < self.vmin:
+                self.vmin = self.val
+                self.tmin.blockSignals(True)
+                self.tmin.setValue(self.vmin)
+                self.tmin.blockSignals(False)
+            elif self.val > self.vmax:
+                self.vmax = self.val
+                self.tmax.blockSignals(True)
+                self.tmax.setValue(self.vmax)
                 self.tmax.blockSignals(False)
 
             self.slider.blockSignals(True)
-            self.slider.setValue(val)
-            self.value_label.setText(f"{val:.3g}")
+            self.slider.setValue(self._float_to_int(self.val))
             self.slider.blockSignals(False)
+            self.value_label.setText(f"{self.val:.3g}")
 
     class MainWindow(QtWidgets.QMainWindow):
         def __init__(self):
@@ -368,19 +342,20 @@ def fit(self):
 
         def on_parameter_change(self, from_fit=False,
                                 report_success=False):
-            if not from_fit:
-                if any(x.fit.isChecked() for x in self.parameters):
-                    saved = minuit.fixed[:]
-                    for i, x in enumerate(self.parameters):
-                        minuit.fixed[i] = not x.fit.isChecked()
-                    from_fit = True
-                    report_success = self.do_fit(plot=False)
-                    self.results_text.clear()
-                    self.results_text.setHtml(minuit._repr_html_())
-                    minuit.fixed = saved
-            else:
+            if any(x.fit.isChecked() for x in self.parameters):
+                saved = minuit.fixed[:]
+                for i, x in enumerate(self.parameters):
+                    minuit.fixed[i] = not x.fit.isChecked()
+                from_fit = True
+                report_success = self.do_fit(plot=False)
                 self.results_text.clear()
                 self.results_text.setHtml(minuit._repr_html_())
+                minuit.fixed = saved
+            elif from_fit:
+                self.results_text.clear()
+                self.results_text.setHtml(minuit._repr_html_())
+            else:
+                self.results_text.clear()
 
             for ax in self.fig.get_axes():
                 ax.clear()

From 7f22e492265f2829548f2eeece0ffa5a3a0d1d25 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Fri, 1 Nov 2024 19:40:57 +0100
Subject: [PATCH 05/49] Added get_ipython import for tests

---
 src/iminuit/minuit.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/iminuit/minuit.py b/src/iminuit/minuit.py
index 3c81f2ee..e66c8d57 100644
--- a/src/iminuit/minuit.py
+++ b/src/iminuit/minuit.py
@@ -2356,6 +2356,7 @@ def interactive(
         Minuit.visualize
         """
         try:
+            from IPython import get_ipython
             if (get_ipython().__class__.__name__ == "ZMQInteractiveShell"
                     and "IPKernelApp" in get_ipython().config):
                 is_jupyter = True

From dae61d0d52f72bc051c9297d8e9b54903640fcf2 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Fri, 1 Nov 2024 19:53:41 +0100
Subject: [PATCH 06/49] Fixed tests

---
 tests/test_draw.py | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tests/test_draw.py b/tests/test_draw.py
index 916449b5..3fd759be 100644
--- a/tests/test_draw.py
+++ b/tests/test_draw.py
@@ -308,8 +308,8 @@ def __call__(self, a, b):
     qtbot.addWidget(mw)
 
     # this should modify slider range
-    assert mw.parameters[0].slider._max == 1
-    assert mw.parameters[1].slider._min == -1
+    assert mw.parameters[0].vmax == 1
+    assert mw.parameters[1].vmin == -1
     with plot.assert_call():
         mw.fit_button.click()
     assert_allclose(m.values, (100, -100), atol=1e-5)
@@ -403,5 +403,8 @@ def __call__(self, par):
     trace_args = TraceArgs()
     m = Minuit(cost, (1, 2))
 
-    qtbot.addWidget(m.interactive(trace_args, qt_exec=False)[1])
+    mw = m.interactive(trace_args, qt_exec=False)[1]
+    qtbot.addWidget(mw)
     assert trace_args.nargs > 0
+    mw.close()
+    mw.deleteLater()

From aa29da3397e8e2601a5315d8891ef1e201299348 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Fri, 1 Nov 2024 19:58:23 +0000
Subject: [PATCH 07/49] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 src/iminuit/cost.py              |  7 +++++
 src/iminuit/minuit.py            |  9 +++++--
 src/iminuit/qtwidget.py          | 46 +++++++++++++++++---------------
 tests/test_draw.py               |  9 +++++--
 tests/test_without_ipywidgets.py |  1 +
 tests/test_without_pyqt6.py      |  1 +
 6 files changed, 47 insertions(+), 26 deletions(-)

diff --git a/src/iminuit/cost.py b/src/iminuit/cost.py
index 31e3235c..c873f788 100644
--- a/src/iminuit/cost.py
+++ b/src/iminuit/cost.py
@@ -111,6 +111,7 @@ class documentation for details.
     cast,
     TYPE_CHECKING,
 )
+
 if TYPE_CHECKING:
     from matplotlib.axes import Axes
     from matplotlib.figure import Figure
@@ -772,6 +773,7 @@ def visualize(
         """
         if fig is None:
             from matplotlib import pyplot as plt
+
             fig = plt.gcf()
 
         n = sum(hasattr(comp, "visualize") for comp in self)
@@ -970,6 +972,7 @@ def visualize(
         """
         if ax is None:
             from matplotlib import pyplot as plt
+
             ax = plt.gca()
 
         x = np.sort(self.data)
@@ -1424,6 +1427,7 @@ def visualize(self, args: Sequence[float], ax: Axes = None) -> None:
     def _visualize(self, args: Sequence[float], ax: Axes) -> None:
         if ax is None:
             from matplotlib import pyplot as plt
+
             ax = plt.gca()
 
         n, ne = self._n_err()
@@ -1889,6 +1893,7 @@ def prediction(self, args: Sequence[float]) -> Tuple[NDArray, NDArray]:
     def _visualize(self, args: Sequence[float], ax: Axes) -> None:
         if ax is None:
             from matplotlib import pyplot as plt
+
             ax = plt.gca()
 
         n, ne = self._n_err()
@@ -2336,6 +2341,7 @@ def visualize(
         """
         if ax is None:
             from matplotlib import pyplot as plt
+
             ax = plt.gca()
 
         if self._ndim > 1:
@@ -2540,6 +2546,7 @@ def visualize(self, args: ArrayLike, ax: Axes = None):
         """
         if ax is None:
             from matplotlib import pyplot as plt
+
             ax = plt.gca()
 
         args = np.atleast_1d(args)
diff --git a/src/iminuit/minuit.py b/src/iminuit/minuit.py
index e66c8d57..18f74e41 100644
--- a/src/iminuit/minuit.py
+++ b/src/iminuit/minuit.py
@@ -2357,8 +2357,11 @@ def interactive(
         """
         try:
             from IPython import get_ipython
-            if (get_ipython().__class__.__name__ == "ZMQInteractiveShell"
-                    and "IPKernelApp" in get_ipython().config):
+
+            if (
+                get_ipython().__class__.__name__ == "ZMQInteractiveShell"
+                and "IPKernelApp" in get_ipython().config
+            ):
                 is_jupyter = True
             else:
                 is_jupyter = False
@@ -2369,9 +2372,11 @@ def interactive(
 
         if is_jupyter:
             from iminuit.ipywidget import make_widget
+
             return make_widget(self, plot, kwargs, raise_on_exception)
         else:
             from iminuit.qtwidget import make_widget
+
             return make_widget(self, plot, kwargs, raise_on_exception, qt_exec)
 
     def _free_parameters(self) -> Set[str]:
diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 4c188556..e5013042 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -37,25 +37,28 @@ def __init__(self, minuit, par, callback):
 
             size_policy = QtWidgets.QSizePolicy(
                 QtWidgets.QSizePolicy.Policy.MinimumExpanding,
-                QtWidgets.QSizePolicy.Policy.Fixed)
+                QtWidgets.QSizePolicy.Policy.Fixed,
+            )
             self.setSizePolicy(size_policy)
             layout = QtWidgets.QVBoxLayout()
             self.setLayout(layout)
 
-            label = QtWidgets.QLabel(
-                par, alignment=QtCore.Qt.AlignmentFlag.AlignCenter)
+            label = QtWidgets.QLabel(par, alignment=QtCore.Qt.AlignmentFlag.AlignCenter)
             label.setMinimumSize(QtCore.QSize(50, 0))
             self.value_label = QtWidgets.QLabel(
-                alignment=QtCore.Qt.AlignmentFlag.AlignCenter)
+                alignment=QtCore.Qt.AlignmentFlag.AlignCenter
+            )
             self.value_label.setMinimumSize(QtCore.QSize(50, 0))
             self.slider = QtWidgets.QSlider(QtCore.Qt.Orientation.Horizontal)
             self.slider.setMinimum(0)
             self.slider.setMaximum(int(1e8))
             self.tmin = QtWidgets.QDoubleSpinBox(
-                alignment=QtCore.Qt.AlignmentFlag.AlignCenter)
+                alignment=QtCore.Qt.AlignmentFlag.AlignCenter
+            )
             self.tmin.setRange(_make_finite(-np.inf), _make_finite(np.inf))
             self.tmax = QtWidgets.QDoubleSpinBox(
-                alignment=QtCore.Qt.AlignmentFlag.AlignCenter)
+                alignment=QtCore.Qt.AlignmentFlag.AlignCenter
+            )
             self.tmax.setRange(_make_finite(-np.inf), _make_finite(np.inf))
             self.tmin.setSizePolicy(size_policy)
             self.tmax.setSizePolicy(size_policy)
@@ -66,8 +69,8 @@ def __init__(self, minuit, par, callback):
             self.fit.setCheckable(True)
             self.fit.setChecked(False)
             size_policy = QtWidgets.QSizePolicy(
-                QtWidgets.QSizePolicy.Policy.Fixed,
-                QtWidgets.QSizePolicy.Policy.Fixed)
+                QtWidgets.QSizePolicy.Policy.Fixed, QtWidgets.QSizePolicy.Policy.Fixed
+            )
             self.fix.setSizePolicy(size_policy)
             self.fit.setSizePolicy(size_policy)
             layout1 = QtWidgets.QHBoxLayout()
@@ -212,7 +215,8 @@ def __init__(self):
             plot_group = QtWidgets.QGroupBox("", parent=interactive_tab)
             size_policy = QtWidgets.QSizePolicy(
                 QtWidgets.QSizePolicy.Policy.MinimumExpanding,
-                QtWidgets.QSizePolicy.Policy.MinimumExpanding)
+                QtWidgets.QSizePolicy.Policy.MinimumExpanding,
+            )
             plot_group.setSizePolicy(size_policy)
             plot_layout = QtWidgets.QVBoxLayout(plot_group)
             # Use pyplot here to allow users to use pyplot in the plot
@@ -237,24 +241,23 @@ def __init__(self):
             button_group = QtWidgets.QGroupBox("", parent=interactive_tab)
             size_policy = QtWidgets.QSizePolicy(
                 QtWidgets.QSizePolicy.Policy.Expanding,
-                QtWidgets.QSizePolicy.Policy.Fixed)
+                QtWidgets.QSizePolicy.Policy.Fixed,
+            )
             button_group.setSizePolicy(size_policy)
             button_layout = QtWidgets.QHBoxLayout(button_group)
             self.fit_button = QtWidgets.QPushButton("Fit", parent=button_group)
-            self.fit_button.setStyleSheet(
-                "background-color: #2196F3; color: white")
+            self.fit_button.setStyleSheet("background-color: #2196F3; color: white")
             self.fit_button.clicked.connect(partial(self.do_fit, plot=True))
             button_layout.addWidget(self.fit_button)
             self.update_button = QtWidgets.QPushButton(
-                "Continuous", parent=button_group)
+                "Continuous", parent=button_group
+            )
             self.update_button.setCheckable(True)
             self.update_button.setChecked(True)
             self.update_button.clicked.connect(self.on_update_button_clicked)
             button_layout.addWidget(self.update_button)
-            self.reset_button = QtWidgets.QPushButton(
-                "Reset", parent=button_group)
-            self.reset_button.setStyleSheet(
-                "background-color: #F44336; color: white")
+            self.reset_button = QtWidgets.QPushButton("Reset", parent=button_group)
+            self.reset_button.setStyleSheet("background-color: #F44336; color: white")
             self.reset_button.clicked.connect(self.on_reset_button_clicked)
             button_layout.addWidget(self.reset_button)
             self.algo_choice = QtWidgets.QComboBox(parent=button_group)
@@ -267,7 +270,8 @@ def __init__(self):
             scroll_area.setWidgetResizable(True)
             size_policy = QtWidgets.QSizePolicy(
                 QtWidgets.QSizePolicy.Policy.MinimumExpanding,
-                QtWidgets.QSizePolicy.Policy.MinimumExpanding)
+                QtWidgets.QSizePolicy.Policy.MinimumExpanding,
+            )
             scroll_area.setSizePolicy(size_policy)
             scroll_area_contents = QtWidgets.QWidget()
             parameter_layout = QtWidgets.QVBoxLayout(scroll_area_contents)
@@ -340,8 +344,7 @@ def fit(self):
                 assert False  # pragma: no cover, should never happen
             return True
 
-        def on_parameter_change(self, from_fit=False,
-                                report_success=False):
+        def on_parameter_change(self, from_fit=False, report_success=False):
             if any(x.fit.isChecked() for x in self.parameters):
                 saved = minuit.fixed[:]
                 for i, x in enumerate(self.parameters):
@@ -368,8 +371,7 @@ def do_fit(self, plot=True):
                 x.reset(val=minuit.values[i])
             if not plot:
                 return report_success
-            self.on_parameter_change(
-                from_fit=True, report_success=report_success)
+            self.on_parameter_change(from_fit=True, report_success=report_success)
 
         def on_update_button_clicked(self):
             for x in self.parameters:
diff --git a/tests/test_draw.py b/tests/test_draw.py
index 3fd759be..647bbaa1 100644
--- a/tests/test_draw.py
+++ b/tests/test_draw.py
@@ -230,6 +230,7 @@ def __call__(self, a, b):
         with plot.assert_call():
             fit_button.click()
 
+
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
 def test_interactive_pyqt6(qtbot):
     PyQt6 = pytest.importorskip("PyQt6")
@@ -314,12 +315,13 @@ def __call__(self, a, b):
         mw.fit_button.click()
     assert_allclose(m.values, (100, -100), atol=1e-5)
     # this should trigger an exception
-    #plot.raises = True
-    #with plot.assert_call():
+    # plot.raises = True
+    # with plot.assert_call():
     #    mw.fit_button.click()
     mw.close()
     mw.deleteLater()
 
+
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
 def test_interactive_ipywidgets_raises():
     pytest.importorskip("ipywidgets")
@@ -341,6 +343,7 @@ def raiser(args):
         with pytest.raises(ValueError):
             m.interactive(raiser, raise_on_exception=True)
 
+
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
 def test_interactive_pyqt6_raises(qtbot):
     pytest.importorskip("PyQt6")
@@ -362,6 +365,7 @@ def raiser(args):
         mw.close()
         mw.deleteLater()
 
+
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
 def test_interactive_ipywidgets_with_array_func():
     pytest.importorskip("ipywidgets")
@@ -387,6 +391,7 @@ def __call__(self, par):
         m.interactive(trace_args)
         assert trace_args.nargs > 0
 
+
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
 def test_interactive_pyqt6_with_array_func(qtbot):
     pytest.importorskip("PyQt6")
diff --git a/tests/test_without_ipywidgets.py b/tests/test_without_ipywidgets.py
index 54365db0..ee1bcf0c 100644
--- a/tests/test_without_ipywidgets.py
+++ b/tests/test_without_ipywidgets.py
@@ -5,6 +5,7 @@
 
 pytest.importorskip("ipywidgets")
 
+
 def test_interactive():
     pytest.importorskip("matplotlib")
     import iminuit
diff --git a/tests/test_without_pyqt6.py b/tests/test_without_pyqt6.py
index 0bc59486..f47bdace 100644
--- a/tests/test_without_pyqt6.py
+++ b/tests/test_without_pyqt6.py
@@ -4,6 +4,7 @@
 
 pytest.importorskip("PyQt6")
 
+
 def test_interactive(qtbot):
     pytest.importorskip("matplotlib")
     import iminuit

From b90fdb1186349de3ba9fa88cf5ecd80200e37615 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Sun, 3 Nov 2024 17:28:55 +0100
Subject: [PATCH 08/49] Only return QMainWindow

---
 src/iminuit/qtwidget.py     | 15 +++++++--------
 tests/test_draw.py          | 12 ++++++------
 tests/test_without_pyqt6.py |  4 ++--
 3 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index e5013042..d7c2cfbf 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -385,16 +385,15 @@ def on_reset_button_clicked(self):
                 x.reset(val=minuit.values[i], limits=original_limits[i])
             self.on_parameter_change()
 
-    # Set up the Qt application
-    app = QtWidgets.QApplication.instance()
-    if app is None:
-        app = QtWidgets.QApplication([])
-    main_window = MainWindow()
-    main_window.show()
-
     if qt_exec:
+        app = QtWidgets.QApplication.instance()
+        if app is None:
+            app = QtWidgets.QApplication([])
+        main_window = MainWindow()
+        main_window.show()
         app.exec()
-    return app, main_window
+    else:
+        return MainWindow()
 
 
 def _make_finite(x: float) -> float:
diff --git a/tests/test_draw.py b/tests/test_draw.py
index 647bbaa1..b60a867e 100644
--- a/tests/test_draw.py
+++ b/tests/test_draw.py
@@ -259,13 +259,13 @@ def assert_call(self):
     m = Minuit(cost, 1, 1)
 
     with pytest.raises(AttributeError, match="no visualize method"):
-        mw = m.interactive(raise_on_exception=True, qt_exec=False)[1]
+        mw = m.interactive(raise_on_exception=True, qt_exec=False)
         qtbot.addWidget(mw)
         mw.close()
         mw.deleteLater()
 
     with plot.assert_call():
-        mw1 = m.interactive(plot, qt_exec=False)[1]
+        mw1 = m.interactive(plot, qt_exec=False)
     qtbot.addWidget(mw1)
     assert isinstance(mw1, PyQt6.QtWidgets.QMainWindow)
 
@@ -305,7 +305,7 @@ def __call__(self, a, b):
     c = Cost()
     m = Minuit(c, 0, 0)
     with plot.assert_call():
-        mw = m.interactive(raise_on_exception=True, qt_exec=False)[1]
+        mw = m.interactive(raise_on_exception=True, qt_exec=False)
     qtbot.addWidget(mw)
 
     # this should modify slider range
@@ -354,13 +354,13 @@ def raiser(args):
     m = Minuit(lambda x, y: 0, 0, 1)
 
     # by default do not raise
-    mw = m.interactive(raiser, qt_exec=False)[1]
+    mw = m.interactive(raiser, qt_exec=False)
     qtbot.addWidget(mw)
     mw.close()
     mw.deleteLater()
 
     with pytest.raises(ValueError):
-        mw = m.interactive(raiser, raise_on_exception=True, qt_exec=False)[1]
+        mw = m.interactive(raiser, raise_on_exception=True, qt_exec=False)
         qtbot.addWidget(mw)
         mw.close()
         mw.deleteLater()
@@ -408,7 +408,7 @@ def __call__(self, par):
     trace_args = TraceArgs()
     m = Minuit(cost, (1, 2))
 
-    mw = m.interactive(trace_args, qt_exec=False)[1]
+    mw = m.interactive(trace_args, qt_exec=False)
     qtbot.addWidget(mw)
     assert trace_args.nargs > 0
     mw.close()
diff --git a/tests/test_without_pyqt6.py b/tests/test_without_pyqt6.py
index f47bdace..54020c73 100644
--- a/tests/test_without_pyqt6.py
+++ b/tests/test_without_pyqt6.py
@@ -10,14 +10,14 @@ def test_interactive(qtbot):
     import iminuit
 
     cost = LeastSquares([1.1, 2.2], [3.3, 4.4], 1, lambda x, a: a * x)
-    mw = iminuit.Minuit(cost, 1).interactive(qt_exec=False)[1]
+    mw = iminuit.Minuit(cost, 1).interactive(qt_exec=False)
     qtbot.addWidget(mw)
     mw.close()
     mw.deleteLater()
 
     with hide_modules("PyQt6", reload="iminuit.qtwidget"):
         with pytest.raises(ModuleNotFoundError, match="Please install"):
-            mw = iminuit.Minuit(cost, 1).interactive(qt_exec=False)[1]
+            mw = iminuit.Minuit(cost, 1).interactive(qt_exec=False)
             qtbot.addWidget(mw)
             mw.close()
             mw.deleteLater()

From 02fc7929701f18fc532ec62fa30222453eba5cc2 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Sun, 3 Nov 2024 22:36:56 +0100
Subject: [PATCH 09/49] Fixed centering in ComboBox

---
 src/iminuit/qtwidget.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index d7c2cfbf..96776b76 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -261,7 +261,9 @@ def __init__(self):
             self.reset_button.clicked.connect(self.on_reset_button_clicked)
             button_layout.addWidget(self.reset_button)
             self.algo_choice = QtWidgets.QComboBox(parent=button_group)
-            self.algo_choice.setStyleSheet("QComboBox { text-align: center; }")
+            self.algo_choice.setEditable(True)
+            self.algo_choice.lineEdit().setAlignment(QtCore.Qt.AlignmentFlag.AlignCenter)
+            self.algo_choice.lineEdit().setReadOnly(True)
             self.algo_choice.addItems(["Migrad", "Scipy", "Simplex"])
             button_layout.addWidget(self.algo_choice)
             interactive_layout.addWidget(button_group, 0, 1, 1, 1)

From cba417d59dda7a7e2a06074eacece2fe8b9f73d1 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sun, 3 Nov 2024 21:37:21 +0000
Subject: [PATCH 10/49] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 src/iminuit/qtwidget.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 96776b76..3682a7ac 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -262,7 +262,9 @@ def __init__(self):
             button_layout.addWidget(self.reset_button)
             self.algo_choice = QtWidgets.QComboBox(parent=button_group)
             self.algo_choice.setEditable(True)
-            self.algo_choice.lineEdit().setAlignment(QtCore.Qt.AlignmentFlag.AlignCenter)
+            self.algo_choice.lineEdit().setAlignment(
+                QtCore.Qt.AlignmentFlag.AlignCenter
+            )
             self.algo_choice.lineEdit().setReadOnly(True)
             self.algo_choice.addItems(["Migrad", "Scipy", "Simplex"])
             button_layout.addWidget(self.algo_choice)

From 9485f85c203db9d276942ecd88a8a1ceff6295df Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Fri, 6 Dec 2024 16:39:30 +0100
Subject: [PATCH 11/49] Added context manager for signal blocking

---
 src/iminuit/qtwidget.py | 84 +++++++++++++++++++++--------------------
 1 file changed, 43 insertions(+), 41 deletions(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 3682a7ac..bf409de3 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -5,6 +5,7 @@
 from typing import Dict, Any, Callable
 import sys
 from functools import partial
+from contextlib import contextmanager
 
 try:
     from PyQt6 import QtCore, QtGui, QtWidgets
@@ -113,42 +114,38 @@ def on_val_changed(self, val):
         def on_min_changed(self):
             tmin = self.tmin.value()
             if tmin >= self.vmax:
-                self.tmin.blockSignals(True)
-                self.tmin.setValue(self.vmin)
-                self.tmin.blockSignals(False)
+                with block_signals(self.tmin):
+                    self.tmin.setValue(self.vmin)
                 return
             self.vmin = tmin
-            self.slider.blockSignals(True)
-            if tmin > self.val:
-                self.val = tmin
-                minuit.values[self.par] = tmin
-                self.slider.setValue(0)
-                self.value_label.setText(f"{self.val:.3g}")
-                self.callback()
-            else:
-                self.slider.setValue(self._float_to_int(self.val))
-            self.slider.blockSignals(False)
+            with block_signals(self.slider):
+                if tmin > self.val:
+                    self.val = tmin
+                    minuit.values[self.par] = tmin
+                    self.slider.setValue(0)
+                    self.value_label.setText(f"{self.val:.3g}")
+                    self.callback()
+                else:
+                    self.slider.setValue(self._float_to_int(self.val))
             lim = minuit.limits[self.par]
             minuit.limits[self.par] = (tmin, lim[1])
 
         def on_max_changed(self):
             tmax = self.tmax.value()
             if tmax <= self.tmin.value():
-                self.tmax.blockSignals(True)
-                self.tmax.setValue(self.vmax)
-                self.tmax.blockSignals(False)
+                with block_signals(self.tmax):
+                    self.tmax.setValue(self.vmax)
                 return
             self.vmax = tmax
-            self.slider.blockSignals(True)
-            if tmax < self.val:
-                self.val = tmax
-                minuit.values[self.par] = tmax
-                self.slider.setValue(int(1e8))
-                self.value_label.setText(f"{self.val:.3g}")
-                self.callback()
-            else:
-                self.slider.setValue(self._float_to_int(self.val))
-            self.slider.blockSignals(False)
+            with block_signals(self.slider):
+                if tmax < self.val:
+                    self.val = tmax
+                    minuit.values[self.par] = tmax
+                    self.slider.setValue(int(1e8))
+                    self.value_label.setText(f"{self.val:.3g}")
+                    self.callback()
+                else:
+                    self.slider.setValue(self._float_to_int(self.val))
             lim = minuit.limits[self.par]
             minuit.limits[self.par] = (lim[0], tmax)
 
@@ -169,28 +166,22 @@ def reset(self, val, limits=None):
                 step = _guess_initial_step(val, vmin, vmax)
                 self.vmin = vmin if np.isfinite(vmin) else val - 100 * step
                 self.vmax = vmax if np.isfinite(vmax) else val + 100 * step
-                self.tmin.blockSignals(True)
-                self.tmin.setValue(self.vmin)
-                self.tmin.blockSignals(False)
-                self.tmax.blockSignals(True)
-                self.tmax.setValue(self.vmax)
-                self.tmax.blockSignals(False)
+                with block_signals(self.tmin, self.tmax):
+                    self.tmin.setValue(self.vmin)
+                    self.tmax.setValue(self.vmax)
 
             self.val = val
             if self.val < self.vmin:
                 self.vmin = self.val
-                self.tmin.blockSignals(True)
-                self.tmin.setValue(self.vmin)
-                self.tmin.blockSignals(False)
+                with block_signals(self.tmin):
+                    self.tmin.setValue(self.vmin)
             elif self.val > self.vmax:
                 self.vmax = self.val
-                self.tmax.blockSignals(True)
-                self.tmax.setValue(self.vmax)
-                self.tmax.blockSignals(False)
+                with block_signals(self.tmax):
+                    self.tmax.setValue(self.vmax)
 
-            self.slider.blockSignals(True)
-            self.slider.setValue(self._float_to_int(self.val))
-            self.slider.blockSignals(False)
+            with block_signals(self.slider):
+                self.slider.setValue(self._float_to_int(self.val))
             self.value_label.setText(f"{self.val:.3g}")
 
     class MainWindow(QtWidgets.QMainWindow):
@@ -400,6 +391,17 @@ def on_reset_button_clicked(self):
         return MainWindow()
 
 
+@contextmanager
+def block_signals(*widgets):
+    for w in widgets:
+        w.blockSignals(True)
+    try:
+        yield
+    finally:
+        for w in widgets:
+            w.blockSignals(False)
+
+
 def _make_finite(x: float) -> float:
     sign = -1 if x < 0 else 1
     if abs(x) == np.inf:

From e20f357b5734260ac69a74a0e50287850bd44d19 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Fri, 6 Dec 2024 16:50:53 +0100
Subject: [PATCH 12/49] Changed partial to lambda

---
 src/iminuit/qtwidget.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index bf409de3..979023ad 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -4,7 +4,6 @@
 import numpy as np
 from typing import Dict, Any, Callable
 import sys
-from functools import partial
 from contextlib import contextmanager
 
 try:
@@ -238,7 +237,7 @@ def __init__(self):
             button_layout = QtWidgets.QHBoxLayout(button_group)
             self.fit_button = QtWidgets.QPushButton("Fit", parent=button_group)
             self.fit_button.setStyleSheet("background-color: #2196F3; color: white")
-            self.fit_button.clicked.connect(partial(self.do_fit, plot=True))
+            self.fit_button.clicked.connect(lambda: self.do_fit(plot=True))
             button_layout.addWidget(self.fit_button)
             self.update_button = QtWidgets.QPushButton(
                 "Continuous", parent=button_group

From 2342b7de04cd52bd47c36f170c4d26a8a5b5ec21 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Fri, 6 Dec 2024 21:22:51 +0100
Subject: [PATCH 13/49] Removed qt_exec arg and changed QMainWindow to QWidget

---
 src/iminuit/minuit.py   | 11 ++++-------
 src/iminuit/qtwidget.py | 16 ++++++----------
 2 files changed, 10 insertions(+), 17 deletions(-)

diff --git a/src/iminuit/minuit.py b/src/iminuit/minuit.py
index 18f74e41..92270c7e 100644
--- a/src/iminuit/minuit.py
+++ b/src/iminuit/minuit.py
@@ -2314,7 +2314,6 @@ def interactive(
         self,
         plot: Callable = None,
         raise_on_exception=False,
-        qt_exec=True,
         **kwargs,
     ):
         """
@@ -2322,8 +2321,9 @@ def interactive(
 
         Starts a fitting application (requires PyQt6, matplotlib) in which the
         fit is visualized and the parameters can be manipulated to find good
-        starting parameters and to debug the fit. The QApplication is executed
-        by default, but can be disabled by setting qt_exec=False.
+        starting parameters and to debug the fit. If there is a QApplication
+        already running, the widget will be returned instead of starting the
+        application.
 
         When called in a Jupyter notebook (requires ipywidgets, IPython, matplotlib),
         a fitting widget is returned instead, which can be displayed.
@@ -2341,8 +2341,6 @@ def interactive(
             The default is to catch exceptions in the plot function and convert them
             into a plotted message. In unit tests, raise_on_exception should be set to
             True to allow detecting errors.
-        qt_exec : bool, optional
-            Whether the PyQt6 application is executed. This is ignored in Jupyter notebooks.
         **kwargs :
             Any other keyword arguments are forwarded to the plot function.
 
@@ -2373,11 +2371,10 @@ def interactive(
         if is_jupyter:
             from iminuit.ipywidget import make_widget
 
-            return make_widget(self, plot, kwargs, raise_on_exception)
         else:
             from iminuit.qtwidget import make_widget
 
-            return make_widget(self, plot, kwargs, raise_on_exception, qt_exec)
+        return make_widget(self, plot, kwargs, raise_on_exception)
 
     def _free_parameters(self) -> Set[str]:
         return set(mp.name for mp in self._last_state if not mp.is_fixed)
diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 979023ad..b3dd603d 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -23,7 +23,6 @@ def make_widget(
     plot: Callable[..., None],
     kwargs: Dict[str, Any],
     raise_on_exception: bool,
-    qt_exec: bool,
 ):
     """Make interactive fitting widget."""
     original_values = minuit.values[:]
@@ -183,7 +182,7 @@ def reset(self, val, limits=None):
                 self.slider.setValue(self._float_to_int(self.val))
             self.value_label.setText(f"{self.val:.3g}")
 
-    class MainWindow(QtWidgets.QMainWindow):
+    class Widget(QtWidgets.QWidget):
         def __init__(self):
             super().__init__()
             self.resize(1200, 600)
@@ -191,7 +190,6 @@ def __init__(self):
             font.setPointSize(12)
             self.setFont(font)
             centralwidget = QtWidgets.QWidget(parent=self)
-            self.setCentralWidget(centralwidget)
             central_layout = QtWidgets.QVBoxLayout(centralwidget)
             tab = QtWidgets.QTabWidget(parent=centralwidget)
             interactive_tab = QtWidgets.QWidget()
@@ -379,15 +377,13 @@ def on_reset_button_clicked(self):
                 x.reset(val=minuit.values[i], limits=original_limits[i])
             self.on_parameter_change()
 
-    if qt_exec:
-        app = QtWidgets.QApplication.instance()
-        if app is None:
-            app = QtWidgets.QApplication([])
-        main_window = MainWindow()
-        main_window.show()
+    if QtWidgets.QApplication.instance() is None:
+        app = QtWidgets.QApplication([])
+        widget = Widget()
+        widget.show()
         app.exec()
     else:
-        return MainWindow()
+        return Widget()
 
 
 @contextmanager

From 92f7c832df87b05e4f6a1b12739e6f250e26dd14 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Fri, 6 Dec 2024 22:36:20 +0100
Subject: [PATCH 14/49] Removed tabs and added more decimals to SpinBox

---
 src/iminuit/qtwidget.py | 48 ++++++++++++++++++++---------------------
 1 file changed, 24 insertions(+), 24 deletions(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index b3dd603d..2d31aa29 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -86,8 +86,12 @@ def __init__(self, minuit, par, callback):
 
             self.reset(minuit.values[par], limits=minuit.limits[par])
 
-            self.tmin.setSingleStep(1e-1 * (self.vmax - self.vmin))
-            self.tmax.setSingleStep(1e-1 * (self.vmax - self.vmin))
+            step_size = 1e-1 * (self.vmax - self.vmin)
+            decimals = max(int(-np.log10(step_size)) + 2, 0)
+            self.tmin.setSingleStep(step_size)
+            self.tmin.setDecimals(decimals)
+            self.tmax.setSingleStep(step_size)
+            self.tmax.setDecimals(decimals)
             self.tmin.setMinimum(_make_finite(minuit.limits[par][0]))
             self.tmax.setMaximum(_make_finite(minuit.limits[par][1]))
 
@@ -185,22 +189,15 @@ def reset(self, val, limits=None):
     class Widget(QtWidgets.QWidget):
         def __init__(self):
             super().__init__()
-            self.resize(1200, 600)
+            self.resize(1200, 800)
             font = QtGui.QFont()
             font.setPointSize(12)
             self.setFont(font)
-            centralwidget = QtWidgets.QWidget(parent=self)
-            central_layout = QtWidgets.QVBoxLayout(centralwidget)
-            tab = QtWidgets.QTabWidget(parent=centralwidget)
-            interactive_tab = QtWidgets.QWidget()
-            tab.addTab(interactive_tab, "Interactive")
-            results_tab = QtWidgets.QWidget()
-            tab.addTab(results_tab, "Results")
-            central_layout.addWidget(tab)
-
-            interactive_layout = QtWidgets.QGridLayout(interactive_tab)
-
-            plot_group = QtWidgets.QGroupBox("", parent=interactive_tab)
+            self.setWindowTitle("iminuit")
+
+            interactive_layout = QtWidgets.QGridLayout(self)
+
+            plot_group = QtWidgets.QGroupBox("", parent=self)
             size_policy = QtWidgets.QSizePolicy(
                 QtWidgets.QSizePolicy.Policy.MinimumExpanding,
                 QtWidgets.QSizePolicy.Policy.MinimumExpanding,
@@ -226,7 +223,7 @@ def __init__(self):
                 pass
             self.fig_width = self.fig.get_figwidth()
 
-            button_group = QtWidgets.QGroupBox("", parent=interactive_tab)
+            button_group = QtWidgets.QGroupBox("", parent=self)
             size_policy = QtWidgets.QSizePolicy(
                 QtWidgets.QSizePolicy.Policy.Expanding,
                 QtWidgets.QSizePolicy.Policy.Fixed,
@@ -258,17 +255,17 @@ def __init__(self):
             button_layout.addWidget(self.algo_choice)
             interactive_layout.addWidget(button_group, 0, 1, 1, 1)
 
-            scroll_area = QtWidgets.QScrollArea()
-            scroll_area.setWidgetResizable(True)
+            par_scroll_area = QtWidgets.QScrollArea()
+            par_scroll_area.setWidgetResizable(True)
             size_policy = QtWidgets.QSizePolicy(
                 QtWidgets.QSizePolicy.Policy.MinimumExpanding,
                 QtWidgets.QSizePolicy.Policy.MinimumExpanding,
             )
-            scroll_area.setSizePolicy(size_policy)
+            par_scroll_area.setSizePolicy(size_policy)
             scroll_area_contents = QtWidgets.QWidget()
             parameter_layout = QtWidgets.QVBoxLayout(scroll_area_contents)
-            scroll_area.setWidget(scroll_area_contents)
-            interactive_layout.addWidget(scroll_area, 1, 1, 1, 1)
+            par_scroll_area.setWidget(scroll_area_contents)
+            interactive_layout.addWidget(par_scroll_area, 1, 1, 2, 1)
             self.parameters = []
             for par in minuit.parameters:
                 parameter = Parameter(minuit, par, self.on_parameter_change)
@@ -276,10 +273,13 @@ def __init__(self):
                 parameter_layout.addWidget(parameter)
             parameter_layout.addStretch()
 
-            results_layout = QtWidgets.QVBoxLayout(results_tab)
-            self.results_text = QtWidgets.QTextEdit(parent=results_tab)
+            results_scroll_area = QtWidgets.QScrollArea()
+            results_scroll_area.setWidgetResizable(True)
+            results_scroll_area.setSizePolicy(size_policy)
+            self.results_text = QtWidgets.QTextEdit(parent=self)
             self.results_text.setReadOnly(True)
-            results_layout.addWidget(self.results_text)
+            results_scroll_area.setWidget(self.results_text)
+            interactive_layout.addWidget(results_scroll_area, 2, 0, 1, 1)
 
             self.plot_with_frame(from_fit=False, report_success=False)
 

From cf0ee819eab450e420997af2b0fc190204d223f5 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Wed, 11 Dec 2024 18:09:14 +0100
Subject: [PATCH 15/49] Moved _make_finite and _guess_initial_step to util

---
 src/iminuit/ipywidget.py | 16 ++--------------
 src/iminuit/qtwidget.py  | 16 ++--------------
 src/iminuit/util.py      | 13 +++++++++++++
 3 files changed, 17 insertions(+), 28 deletions(-)

diff --git a/src/iminuit/ipywidget.py b/src/iminuit/ipywidget.py
index f56bdeef..f006cf01 100644
--- a/src/iminuit/ipywidget.py
+++ b/src/iminuit/ipywidget.py
@@ -1,9 +1,10 @@
 """Interactive fitting widget for Jupyter notebooks."""
 
+from .util import _widget_guess_initial_step as _guess_initial_step
+from .util import _widget_make_finite as _make_finite
 import warnings
 import numpy as np
 from typing import Dict, Any, Callable
-import sys
 
 with warnings.catch_warnings():
     # ipywidgets produces deprecation warnings through use of internal APIs :(
@@ -277,18 +278,5 @@ def reset(self, value, limits=None):
     return widgets.HBox([out, ui])
 
 
-def _make_finite(x: float) -> float:
-    sign = -1 if x < 0 else 1
-    if abs(x) == np.inf:
-        return sign * sys.float_info.max
-    return x
-
-
-def _guess_initial_step(val: float, vmin: float, vmax: float) -> float:
-    if np.isfinite(vmin) and np.isfinite(vmax):
-        return 1e-2 * (vmax - vmin)
-    return 1e-2
-
-
 def _round(x: float) -> float:
     return float(f"{x:.1g}")
diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 2d31aa29..28ccdb5d 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -1,9 +1,10 @@
 """Interactive fitting widget using PyQt6."""
 
+from .util import _widget_guess_initial_step as _guess_initial_step
+from .util import _widget_make_finite as _make_finite
 import warnings
 import numpy as np
 from typing import Dict, Any, Callable
-import sys
 from contextlib import contextmanager
 
 try:
@@ -395,16 +396,3 @@ def block_signals(*widgets):
     finally:
         for w in widgets:
             w.blockSignals(False)
-
-
-def _make_finite(x: float) -> float:
-    sign = -1 if x < 0 else 1
-    if abs(x) == np.inf:
-        return sign * sys.float_info.max
-    return x
-
-
-def _guess_initial_step(val: float, vmin: float, vmax: float) -> float:
-    if np.isfinite(vmin) and np.isfinite(vmax):
-        return 1e-2 * (vmax - vmin)
-    return 1e-2
diff --git a/src/iminuit/util.py b/src/iminuit/util.py
index 3db8bb51..8df75095 100644
--- a/src/iminuit/util.py
+++ b/src/iminuit/util.py
@@ -1684,3 +1684,16 @@ def is_positive_definite(m: ArrayLike) -> bool:
             return False
         return True
     return False
+
+
+def _widget_make_finite(x: float) -> float:
+    sign = -1 if x < 0 else 1
+    if abs(x) == np.inf:
+        return sign * sys.float_info.max
+    return x
+
+
+def _widget_guess_initial_step(val: float, vmin: float, vmax: float) -> float:
+    if np.isfinite(vmin) and np.isfinite(vmax):
+        return 1e-2 * (vmax - vmin)
+    return 1e-2

From 7a6f7afa2112432efaacecb17a7fe9d12511bf7e Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Wed, 11 Dec 2024 18:30:49 +0100
Subject: [PATCH 16/49] Changed starting of event loop

---
 src/iminuit/qtwidget.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 28ccdb5d..d8fab513 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -378,11 +378,17 @@ def on_reset_button_clicked(self):
                 x.reset(val=minuit.values[i], limits=original_limits[i])
             self.on_parameter_change()
 
-    if QtWidgets.QApplication.instance() is None:
+    app = QtWidgets.QApplication.instance()
+    if app is None:
         app = QtWidgets.QApplication([])
+        app.setApplicationName("iminuit")
         widget = Widget()
         widget.show()
-        app.exec()
+        app.exec()  # this blocks the main thread
+    elif app.applicationName() == "iminuit":
+        widget = Widget()
+        widget.show()
+        app.exec()  # this blocks the main thread
     else:
         return Widget()
 

From 1ba806509c8ee09633a78bfa31fb4133c5a8dfb1 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Wed, 11 Dec 2024 20:39:16 +0100
Subject: [PATCH 17/49] Removed unnecessary lines

---
 tests/test_without_pyqt6.py | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/tests/test_without_pyqt6.py b/tests/test_without_pyqt6.py
index 54020c73..0c746487 100644
--- a/tests/test_without_pyqt6.py
+++ b/tests/test_without_pyqt6.py
@@ -10,14 +10,7 @@ def test_interactive(qtbot):
     import iminuit
 
     cost = LeastSquares([1.1, 2.2], [3.3, 4.4], 1, lambda x, a: a * x)
-    mw = iminuit.Minuit(cost, 1).interactive(qt_exec=False)
-    qtbot.addWidget(mw)
-    mw.close()
-    mw.deleteLater()
 
     with hide_modules("PyQt6", reload="iminuit.qtwidget"):
         with pytest.raises(ModuleNotFoundError, match="Please install"):
-            mw = iminuit.Minuit(cost, 1).interactive(qt_exec=False)
-            qtbot.addWidget(mw)
-            mw.close()
-            mw.deleteLater()
+            iminuit.Minuit(cost, 1).interactive()

From 0901a462d8312672b13fd7822cf50d93f060557c Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Wed, 11 Dec 2024 21:58:13 +0100
Subject: [PATCH 18/49] Clean up

---
 tests/test_draw.py | 197 ++++++++++++++++++++-------------------------
 1 file changed, 86 insertions(+), 111 deletions(-)

diff --git a/tests/test_draw.py b/tests/test_draw.py
index b60a867e..49fe7636 100644
--- a/tests/test_draw.py
+++ b/tests/test_draw.py
@@ -34,6 +34,16 @@ def fig(request):
     plt.close()
 
 
+@pytest.fixture
+def mock_ipython():
+    with patch("IPython.get_ipython") as mock_get_ipython:
+        mock_shell = MagicMock()
+        mock_shell.__class__.__name__ = "ZMQInteractiveShell"
+        mock_shell.config = {"IPKernelApp": True}
+        mock_get_ipython.return_value = mock_shell
+        yield
+
+
 @pytest.mark.parametrize("arg", ("x", 1))
 def test_profile_1(fig, minuit, arg):
     minuit.draw_profile(arg)
@@ -137,7 +147,7 @@ def test_mnmatrix_7(fig):
 
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_ipywidgets():
+def test_interactive_ipywidgets(mock_ipython):
     ipywidgets = pytest.importorskip("ipywidgets")
 
     def cost(a, b):
@@ -163,72 +173,66 @@ def assert_call(self):
 
     m = Minuit(cost, 1, 1)
 
-    with patch("IPython.get_ipython") as mock_get_ipython:
-        mock_shell = MagicMock()
-        mock_shell.__class__.__name__ = "ZMQInteractiveShell"
-        mock_shell.config = {"IPKernelApp": True}
-        mock_get_ipython.return_value = mock_shell
+    with pytest.raises(AttributeError, match="no visualize method"):
+        m.interactive(raise_on_exception=True)
+
+    with plot.assert_call():
+        out1 = m.interactive(plot)
+    assert isinstance(out1, ipywidgets.HBox)
+
+    # manipulate state to also check this code
+    ui = out1.children[1]
+    header, parameters = ui.children
+    fit_button, update_button, reset_button, algo_select = header.children
+    with plot.assert_call():
+        fit_button.click()
+    assert_allclose(m.values, (0, 0), atol=1e-5)
+    with plot.assert_call():
+        reset_button.click()
+    assert_allclose(m.values, (1, 1), atol=1e-5)
+
+    algo_select.value = "Scipy"
+    with plot.assert_call():
+        fit_button.click()
+
+    algo_select.value = "Simplex"
+    with plot.assert_call():
+        fit_button.click()
+
+    update_button.value = False
+    with plot.assert_call():
+        # because of implementation details, we have to trigger the slider several times
+        for i in range(5):
+            parameters.children[0].slider.value = i  # change first slider
+    parameters.children[0].fix.value = True
+    with plot.assert_call():
+        parameters.children[0].fit.value = True
+
+    class Cost:
+        def visualize(self, args):
+            return plot(args)
+
+        def __call__(self, a, b):
+            return (a - 100) ** 2 + (b + 100) ** 2
+
+    c = Cost()
+    m = Minuit(c, 0, 0)
+    with plot.assert_call():
+        out = m.interactive(raise_on_exception=True)
 
-        with pytest.raises(AttributeError, match="no visualize method"):
-            m.interactive(raise_on_exception=True)
-
-        with plot.assert_call():
-            out1 = m.interactive(plot)
-        assert isinstance(out1, ipywidgets.HBox)
-
-        # manipulate state to also check this code
-        ui = out1.children[1]
-        header, parameters = ui.children
-        fit_button, update_button, reset_button, algo_select = header.children
-        with plot.assert_call():
-            fit_button.click()
-        assert_allclose(m.values, (0, 0), atol=1e-5)
-        with plot.assert_call():
-            reset_button.click()
-        assert_allclose(m.values, (1, 1), atol=1e-5)
-
-        algo_select.value = "Scipy"
-        with plot.assert_call():
-            fit_button.click()
-
-        algo_select.value = "Simplex"
-        with plot.assert_call():
-            fit_button.click()
-
-        update_button.value = False
-        with plot.assert_call():
-            # because of implementation details, we have to trigger the slider several times
-            for i in range(5):
-                parameters.children[0].slider.value = i  # change first slider
-        parameters.children[0].fix.value = True
-        with plot.assert_call():
-            parameters.children[0].fit.value = True
-
-        class Cost:
-            def visualize(self, args):
-                return plot(args)
-
-            def __call__(self, a, b):
-                return (a - 100) ** 2 + (b + 100) ** 2
-
-        c = Cost()
-        m = Minuit(c, 0, 0)
-        with plot.assert_call():
-            out = m.interactive(raise_on_exception=True)
-
-        # this should modify slider range
-        ui = out.children[1]
-        header, parameters = ui.children
-        fit_button, update_button, reset_button, algo_select = header.children
-        assert parameters.children[0].slider.max == 1
-        assert parameters.children[1].slider.min == -1
-        with plot.assert_call():
-            fit_button.click()
-        assert_allclose(m.values, (100, -100), atol=1e-5)
-        # this should trigger an exception
-        plot.raises = True
-        with plot.assert_call():
-            fit_button.click()
+    # this should modify slider range
+    ui = out.children[1]
+    header, parameters = ui.children
+    fit_button, update_button, reset_button, algo_select = header.children
+    assert parameters.children[0].slider.max == 1
+    assert parameters.children[1].slider.min == -1
+    with plot.assert_call():
+        fit_button.click()
+    assert_allclose(m.values, (100, -100), atol=1e-5)
+    # this should trigger an exception
+    plot.raises = True
+    with plot.assert_call():
+        fit_button.click()
 
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
@@ -259,15 +263,12 @@ def assert_call(self):
     m = Minuit(cost, 1, 1)
 
     with pytest.raises(AttributeError, match="no visualize method"):
-        mw = m.interactive(raise_on_exception=True, qt_exec=False)
-        qtbot.addWidget(mw)
-        mw.close()
-        mw.deleteLater()
+        m.interactive(raise_on_exception=True)
 
     with plot.assert_call():
-        mw1 = m.interactive(plot, qt_exec=False)
+        mw1 = m.interactive(plot)
     qtbot.addWidget(mw1)
-    assert isinstance(mw1, PyQt6.QtWidgets.QMainWindow)
+    assert isinstance(mw1, PyQt6.QtWidgets.QWidget)
 
     # manipulate state to also check this code
     with plot.assert_call():
@@ -292,9 +293,6 @@ def assert_call(self):
     with plot.assert_call():
         mw1.parameters[0].fit.click()
 
-    mw1.close()
-    mw1.deleteLater()
-
     class Cost:
         def visualize(self, args):
             return plot(args)
@@ -305,7 +303,7 @@ def __call__(self, a, b):
     c = Cost()
     m = Minuit(c, 0, 0)
     with plot.assert_call():
-        mw = m.interactive(raise_on_exception=True, qt_exec=False)
+        mw = m.interactive(raise_on_exception=True)
     qtbot.addWidget(mw)
 
     # this should modify slider range
@@ -315,15 +313,13 @@ def __call__(self, a, b):
         mw.fit_button.click()
     assert_allclose(m.values, (100, -100), atol=1e-5)
     # this should trigger an exception
-    # plot.raises = True
-    # with plot.assert_call():
+    #plot.raises = True
+    #with plot.assert_call():
     #    mw.fit_button.click()
-    mw.close()
-    mw.deleteLater()
 
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_ipywidgets_raises():
+def test_interactive_ipywidgets_raises(mock_ipython):
     pytest.importorskip("ipywidgets")
 
     def raiser(args):
@@ -332,16 +328,10 @@ def raiser(args):
     m = Minuit(lambda x, y: 0, 0, 1)
 
     # by default do not raise
-    with patch("IPython.get_ipython") as mock_get_ipython:
-        mock_shell = MagicMock()
-        mock_shell.__class__.__name__ = "ZMQInteractiveShell"
-        mock_shell.config = {"IPKernelApp": True}
-        mock_get_ipython.return_value = mock_shell
+    m.interactive(raiser)
 
-        m.interactive(raiser)
-
-        with pytest.raises(ValueError):
-            m.interactive(raiser, raise_on_exception=True)
+    with pytest.raises(ValueError):
+        m.interactive(raiser, raise_on_exception=True)
 
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
@@ -354,20 +344,14 @@ def raiser(args):
     m = Minuit(lambda x, y: 0, 0, 1)
 
     # by default do not raise
-    mw = m.interactive(raiser, qt_exec=False)
-    qtbot.addWidget(mw)
-    mw.close()
-    mw.deleteLater()
+    m.interactive(raiser)
 
     with pytest.raises(ValueError):
-        mw = m.interactive(raiser, raise_on_exception=True, qt_exec=False)
-        qtbot.addWidget(mw)
-        mw.close()
-        mw.deleteLater()
+        m.interactive(raiser, raise_on_exception=True)
 
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_ipywidgets_with_array_func():
+def test_interactive_ipywidgets_with_array_func(mock_ipython):
     pytest.importorskip("ipywidgets")
 
     def cost(par):
@@ -382,14 +366,8 @@ def __call__(self, par):
     trace_args = TraceArgs()
     m = Minuit(cost, (1, 2))
 
-    with patch("IPython.get_ipython") as mock_get_ipython:
-        mock_shell = MagicMock()
-        mock_shell.__class__.__name__ = "ZMQInteractiveShell"
-        mock_shell.config = {"IPKernelApp": True}
-        mock_get_ipython.return_value = mock_shell
-
-        m.interactive(trace_args)
-        assert trace_args.nargs > 0
+    m.interactive(trace_args)
+    assert trace_args.nargs > 0
 
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
@@ -408,8 +386,5 @@ def __call__(self, par):
     trace_args = TraceArgs()
     m = Minuit(cost, (1, 2))
 
-    mw = m.interactive(trace_args, qt_exec=False)
-    qtbot.addWidget(mw)
+    m.interactive(trace_args)
     assert trace_args.nargs > 0
-    mw.close()
-    mw.deleteLater()

From f7c4fd5342e8621032a66dbe5980dd9b230de212 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Wed, 11 Dec 2024 22:17:47 +0100
Subject: [PATCH 19/49] Moved mock ipython fixture to conftest.py

---
 tests/conftest.py                | 11 +++++++++++
 tests/test_draw.py               | 10 ----------
 tests/test_without_ipywidgets.py | 17 +++++------------
 3 files changed, 16 insertions(+), 22 deletions(-)
 create mode 100644 tests/conftest.py

diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 00000000..f8096e30
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,11 @@
+import pytest
+from unittest.mock import patch, MagicMock
+
+@pytest.fixture
+def mock_ipython():
+    with patch("IPython.get_ipython") as mock_get_ipython:
+        mock_shell = MagicMock()
+        mock_shell.__class__.__name__ = "ZMQInteractiveShell"
+        mock_shell.config = {"IPKernelApp": True}
+        mock_get_ipython.return_value = mock_shell
+        yield
diff --git a/tests/test_draw.py b/tests/test_draw.py
index 49fe7636..b0c165cb 100644
--- a/tests/test_draw.py
+++ b/tests/test_draw.py
@@ -34,16 +34,6 @@ def fig(request):
     plt.close()
 
 
-@pytest.fixture
-def mock_ipython():
-    with patch("IPython.get_ipython") as mock_get_ipython:
-        mock_shell = MagicMock()
-        mock_shell.__class__.__name__ = "ZMQInteractiveShell"
-        mock_shell.config = {"IPKernelApp": True}
-        mock_get_ipython.return_value = mock_shell
-        yield
-
-
 @pytest.mark.parametrize("arg", ("x", 1))
 def test_profile_1(fig, minuit, arg):
     minuit.draw_profile(arg)
diff --git a/tests/test_without_ipywidgets.py b/tests/test_without_ipywidgets.py
index ee1bcf0c..7e2df799 100644
--- a/tests/test_without_ipywidgets.py
+++ b/tests/test_without_ipywidgets.py
@@ -1,25 +1,18 @@
 from iminuit._hide_modules import hide_modules
 from iminuit.cost import LeastSquares
 import pytest
-from unittest.mock import patch, MagicMock
 
 pytest.importorskip("ipywidgets")
 
 
-def test_interactive():
+def test_interactive(mock_ipython):
     pytest.importorskip("matplotlib")
     import iminuit
 
     cost = LeastSquares([1.1, 2.2], [3.3, 4.4], 1, lambda x, a: a * x)
 
-    with patch("IPython.get_ipython") as mock_get_ipython:
-        mock_shell = MagicMock()
-        mock_shell.__class__.__name__ = "ZMQInteractiveShell"
-        mock_shell.config = {"IPKernelApp": True}
-        mock_get_ipython.return_value = mock_shell
+    iminuit.Minuit(cost, 1).interactive()
 
-        iminuit.Minuit(cost, 1).interactive()
-
-        with hide_modules("ipywidgets", reload="iminuit.ipywidget"):
-            with pytest.raises(ModuleNotFoundError, match="Please install"):
-                iminuit.Minuit(cost, 1).interactive()
+    with hide_modules("ipywidgets", reload="iminuit.ipywidget"):
+        with pytest.raises(ModuleNotFoundError, match="Please install"):
+            iminuit.Minuit(cost, 1).interactive()

From 2813c5131db0e6fe1024ba39d3725937fdc9bb31 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Wed, 11 Dec 2024 21:31:31 +0000
Subject: [PATCH 20/49] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 tests/conftest.py  | 1 +
 tests/test_draw.py | 5 ++---
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/tests/conftest.py b/tests/conftest.py
index f8096e30..eb4b20fa 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,6 +1,7 @@
 import pytest
 from unittest.mock import patch, MagicMock
 
+
 @pytest.fixture
 def mock_ipython():
     with patch("IPython.get_ipython") as mock_get_ipython:
diff --git a/tests/test_draw.py b/tests/test_draw.py
index b0c165cb..699fc415 100644
--- a/tests/test_draw.py
+++ b/tests/test_draw.py
@@ -4,7 +4,6 @@
 import numpy as np
 from numpy.testing import assert_allclose
 import contextlib
-from unittest.mock import patch, MagicMock
 
 mpl = pytest.importorskip("matplotlib")
 plt = pytest.importorskip("matplotlib.pyplot")
@@ -303,8 +302,8 @@ def __call__(self, a, b):
         mw.fit_button.click()
     assert_allclose(m.values, (100, -100), atol=1e-5)
     # this should trigger an exception
-    #plot.raises = True
-    #with plot.assert_call():
+    # plot.raises = True
+    # with plot.assert_call():
     #    mw.fit_button.click()
 
 

From a50b5e52cff4a492f1a24ebf1c65e38ac60c4f34 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Wed, 11 Dec 2024 23:24:25 +0100
Subject: [PATCH 21/49] Removed repeated lines

---
 src/iminuit/qtwidget.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index d8fab513..0607fdc6 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -382,10 +382,8 @@ def on_reset_button_clicked(self):
     if app is None:
         app = QtWidgets.QApplication([])
         app.setApplicationName("iminuit")
-        widget = Widget()
-        widget.show()
-        app.exec()  # this blocks the main thread
-    elif app.applicationName() == "iminuit":
+
+    if app.applicationName() == "iminuit":
         widget = Widget()
         widget.show()
         app.exec()  # this blocks the main thread

From b1fbd3f22a60d30f771c8d970933b8b2063cea15 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Thu, 12 Dec 2024 01:53:32 +0100
Subject: [PATCH 22/49] Back to pyplot

---
 src/iminuit/cost.py     | 114 +++++++++++-----------------------------
 src/iminuit/qtwidget.py |  37 +++++--------
 2 files changed, 46 insertions(+), 105 deletions(-)

diff --git a/src/iminuit/cost.py b/src/iminuit/cost.py
index c873f788..76a75436 100644
--- a/src/iminuit/cost.py
+++ b/src/iminuit/cost.py
@@ -109,12 +109,7 @@ class documentation for details.
     TypeVar,
     Callable,
     cast,
-    TYPE_CHECKING,
 )
-
-if TYPE_CHECKING:
-    from matplotlib.axes import Axes
-    from matplotlib.figure import Figure
 import warnings
 from ._deprecated import deprecated_parameter
 
@@ -744,10 +739,7 @@ def __getitem__(self, key):
         return self._items.__getitem__(key)
 
     def visualize(
-        self,
-        args: Sequence[float],
-        component_kwargs: Dict[int, Dict[str, Any]] = None,
-        fig: Figure = None,
+        self, args: Sequence[float], component_kwargs: Dict[int, Dict[str, Any]] = None
     ):
         """
         Visualize data and model agreement (requires matplotlib).
@@ -765,27 +757,16 @@ def visualize(
             Dict that maps an index to dict of keyword arguments. This can be
             used to pass keyword arguments to a visualize method of a component with
             that index.
-        fig : Figure, optional
-            The matplotlib figure into which the visualization is drawn.
-            If None is passed, the current figure is used. If the passed figure
-            has the same number of axes as there are components with a visualize
-            method, the axes are reused. Otherwise, new axes are created.
+        **kwargs :
+            Other keyword arguments are forwarded to all components.
         """
-        if fig is None:
-            from matplotlib import pyplot as plt
-
-            fig = plt.gcf()
+        from matplotlib import pyplot as plt
 
         n = sum(hasattr(comp, "visualize") for comp in self)
 
+        fig = plt.gcf()
         fig.set_figwidth(n * fig.get_figwidth() / 1.5)
-        ax = fig.get_axes()
-        if len(ax) != n:
-            fig.clear()
-            _, ax = fig.subplots(1, n)
-            # For some reason fig.subplots does not return axes array but only
-            # a single axes even for n > 1
-            ax = fig.get_axes()
+        _, ax = plt.subplots(1, n, num=fig.number)
 
         if component_kwargs is None:
             component_kwargs = {}
@@ -795,7 +776,8 @@ def visualize(
             if not hasattr(comp, "visualize"):
                 continue
             kwargs = component_kwargs.get(k, {})
-            comp.visualize(cargs, ax=ax[i], **kwargs)
+            plt.sca(ax[i])
+            comp.visualize(cargs, **kwargs)
             i += 1
 
 
@@ -949,7 +931,6 @@ def visualize(
         args: Sequence[float],
         model_points: Union[int, Sequence[float]] = 0,
         bins: int = 50,
-        ax: Axes = None,
     ):
         """
         Visualize data and model agreement (requires matplotlib).
@@ -966,14 +947,8 @@ def visualize(
             it is interpreted as the point locations.
         bins : int, optional
             number of bins. Default is 50 bins.
-        ax : Axes, optional
-            The matplotlib axes into which the visualization is drawn.
-            If None is passed, the current axes is used.
         """
-        if ax is None:
-            from matplotlib import pyplot as plt
-
-            ax = plt.gca()
+        from matplotlib import pyplot as plt
 
         x = np.sort(self.data)
 
@@ -999,8 +974,8 @@ def visualize(
         cx = 0.5 * (xe[1:] + xe[:-1])
         dx = xe[1] - xe[0]
 
-        ax.errorbar(cx, n, n**0.5, fmt="ok")
-        ax.fill_between(xm, 0, ym * dx, fc="C0")
+        plt.errorbar(cx, n, n**0.5, fmt="ok")
+        plt.fill_between(xm, 0, ym * dx, fc="C0")
 
     def fisher_information(self, *args: float) -> NDArray:
         """
@@ -1400,7 +1375,7 @@ def prediction(
         """
         return self._pred(args)
 
-    def visualize(self, args: Sequence[float], ax: Axes = None) -> None:
+    def visualize(self, args: Sequence[float]) -> None:
         """
         Visualize data and model agreement (requires matplotlib).
 
@@ -1410,9 +1385,6 @@ def visualize(self, args: Sequence[float], ax: Axes = None) -> None:
         ----------
         args : sequence of float
             Parameter values.
-        ax : Axes, optional
-            The matplotlib axes into which the visualization is drawn.
-            If None is passed, the current axes is used.
 
         Notes
         -----
@@ -1422,13 +1394,10 @@ def visualize(self, args: Sequence[float], ax: Axes = None) -> None:
         comparison to a model, the visualization shows all data bins as a single
         sequence.
         """
-        return self._visualize(args, ax)
-
-    def _visualize(self, args: Sequence[float], ax: Axes) -> None:
-        if ax is None:
-            from matplotlib import pyplot as plt
+        return self._visualize(args)
 
-            ax = plt.gca()
+    def _visualize(self, args: Sequence[float]) -> None:
+        from matplotlib import pyplot as plt
 
         n, ne = self._n_err()
         mu = self.prediction(args)
@@ -1445,9 +1414,8 @@ def _visualize(self, args: Sequence[float], ax: Axes) -> None:
         else:
             xe = self.xe
             cx = 0.5 * (xe[1:] + xe[:-1])
-
-        ax.errorbar(cx, n, ne, fmt="ok")
-        ax.stairs(mu, xe, fill=True, color="C0")
+        plt.errorbar(cx, n, ne, fmt="ok")
+        plt.stairs(mu, xe, fill=True, color="C0")
 
     @abc.abstractmethod
     def _pred(
@@ -1890,11 +1858,8 @@ def prediction(self, args: Sequence[float]) -> Tuple[NDArray, NDArray]:
         mu, mu_var = self._pred(args)
         return mu, np.sqrt(mu_var)
 
-    def _visualize(self, args: Sequence[float], ax: Axes) -> None:
-        if ax is None:
-            from matplotlib import pyplot as plt
-
-            ax = plt.gca()
+    def _visualize(self, args: Sequence[float]) -> None:
+        from matplotlib import pyplot as plt
 
         n, ne = self._n_err()
         mu, mue = self.prediction(args)  # type: ignore
@@ -1911,11 +1876,11 @@ def _visualize(self, args: Sequence[float], ax: Axes) -> None:
             xe = self.xe
             cx = 0.5 * (xe[1:] + xe[:-1])
 
-        ax.errorbar(cx, n, ne, fmt="ok")
+        plt.errorbar(cx, n, ne, fmt="ok")
 
         # need fill=True and fill=False so that bins with mue=0 show up
         for fill in (False, True):
-            ax.stairs(mu + mue, xe, baseline=mu - mue, fill=fill, color="C0")
+            plt.stairs(mu + mue, xe, baseline=mu - mue, fill=fill, color="C0")
 
     def _pulls(self, args: Sequence[float]) -> NDArray:
         mu, mue = self.prediction(args)
@@ -2316,10 +2281,7 @@ def _ndata(self):
         return len(self._masked)
 
     def visualize(
-        self,
-        args: ArrayLike,
-        model_points: Union[int, Sequence[float]] = 0,
-        ax: Axes = None,
+        self, args: ArrayLike, model_points: Union[int, Sequence[float]] = 0
     ) -> Tuple[Tuple[NDArray, NDArray, NDArray], Tuple[NDArray, NDArray]]:
         """
         Visualize data and model agreement (requires matplotlib).
@@ -2335,20 +2297,14 @@ def visualize(
             How many points to use to draw the model. Default is 0, in this case
             an smart sampling algorithm selects the number of points. If array-like,
             it is interpreted as the point locations.
-        ax : Axes, optional
-            The matplotlib axes into which the visualization is drawn.
-            If None is passed, the current axes is used.
         """
-        if ax is None:
-            from matplotlib import pyplot as plt
-
-            ax = plt.gca()
+        from matplotlib import pyplot as plt
 
         if self._ndim > 1:
             raise ValueError("visualize is not implemented for multi-dimensional data")
 
         x, y, ye = self._masked.T
-        ax.errorbar(x, y, ye, fmt="ok")
+        plt.errorbar(x, y, ye, fmt="ok")
         if isinstance(model_points, Iterable):
             xm = np.array(model_points)
             ym = self.model(xm, *args)
@@ -2360,7 +2316,7 @@ def visualize(
             ym = self.model(xm, *args)
         else:
             xm, ym = _smart_sampling(lambda x: self.model(x, *args), x[0], x[-1])
-        ax.plot(xm, ym)
+        plt.plot(xm, ym)
         return (x, y, ye), (xm, ym)
 
     def prediction(self, args: Sequence[float]) -> NDArray:
@@ -2530,7 +2486,7 @@ def _has_grad(self) -> bool:
     def _ndata(self):
         return len(self._expected)
 
-    def visualize(self, args: ArrayLike, ax: Axes = None):
+    def visualize(self, args: ArrayLike):
         """
         Visualize data and model agreement (requires matplotlib).
 
@@ -2540,14 +2496,8 @@ def visualize(self, args: ArrayLike, ax: Axes = None):
         ----------
         args : array-like
             Parameter values.
-        ax : Axes, optional
-            The matplotlib axes into which the visualization is drawn.
-            If None is passed, the current axes is used.
         """
-        if ax is None:
-            from matplotlib import pyplot as plt
-
-            ax = plt.gca()
+        from matplotlib import pyplot as plt
 
         args = np.atleast_1d(args)
 
@@ -2565,14 +2515,14 @@ def visualize(self, args: ArrayLike, ax: Axes = None):
         for v, e, a in zip(val, err, args):
             pull = (a - v) / e
             max_pull = max(abs(pull), max_pull)
-            ax.errorbar(pull, -i, 0, 1, fmt="o", color="C0")
+            plt.errorbar(pull, -i, 0, 1, fmt="o", color="C0")
             i += 1
-        ax.axvline(0, color="k")
-        ax.set_xlim(-max_pull - 1.1, max_pull + 1.1)
-        yaxis = ax.yaxis
+        plt.axvline(0, color="k")
+        plt.xlim(-max_pull - 1.1, max_pull + 1.1)
+        yaxis = plt.gca().yaxis
         yaxis.set_ticks(-np.arange(n))
         yaxis.set_ticklabels(par)
-        ax.set_ylim(-n + 0.5, 0.5)
+        plt.ylim(-n + 0.5, 0.5)
 
 
 def _norm(value: ArrayLike) -> NDArray:
diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 0607fdc6..ecdb108d 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -205,24 +205,14 @@ def __init__(self):
             )
             plot_group.setSizePolicy(size_policy)
             plot_layout = QtWidgets.QVBoxLayout(plot_group)
-            # Use pyplot here to allow users to use pyplot in the plot
-            # function (not recommended / unstable)
-            self.fig, ax = plt.subplots()
-            self.canvas = FigureCanvasQTAgg(self.fig)
+            fig = plt.figure()
+            self.figsize = fig.get_size_inches()
+            manager = plt.get_current_fig_manager()
+            self.canvas = FigureCanvasQTAgg(fig)
+            self.canvas.manager = manager
             plot_layout.addWidget(self.canvas)
             plot_layout.addStretch()
             interactive_layout.addWidget(plot_group, 0, 0, 2, 1)
-            try:
-                plot(minuit.values, fig=self.fig)
-                kwargs["fig"] = self.fig
-            except Exception:
-                pass
-            try:
-                plot(minuit.values, ax=ax)
-                kwargs["ax"] = ax
-            except Exception:
-                pass
-            self.fig_width = self.fig.get_figwidth()
 
             button_group = QtWidgets.QGroupBox("", parent=self)
             size_policy = QtWidgets.QSizePolicy(
@@ -285,7 +275,7 @@ def __init__(self):
             self.plot_with_frame(from_fit=False, report_success=False)
 
         def plot_with_frame(self, from_fit, report_success):
-            self.fig.set_figwidth(self.fig_width)
+            trans = plt.gca().transAxes
             try:
                 with warnings.catch_warnings():
                     minuit.visualize(plot, **kwargs)
@@ -295,7 +285,7 @@ def plot_with_frame(self, from_fit, report_success):
 
                 import traceback
 
-                self.fig.text(
+                plt.figtext(
                     0,
                     0.5,
                     traceback.format_exc(limit=-1),
@@ -308,19 +298,19 @@ def plot_with_frame(self, from_fit, report_success):
                 return
 
             fval = minuit.fmin.fval if from_fit else minuit._fcn(minuit.values)
-            self.fig.get_axes()[0].text(
+            plt.text(
                 0.05,
                 1.05,
                 f"FCN = {fval:.3f}",
-                transform=self.fig.get_axes()[0].transAxes,
+                transform=trans,
                 fontsize="x-large",
             )
             if from_fit and report_success:
-                self.fig.get_axes()[-1].text(
+                plt.text(
                     0.95,
                     1.05,
                     f"{'success' if minuit.valid and minuit.accurate else 'FAILURE'}",
-                    transform=self.fig.get_axes()[-1].transAxes,
+                    transform=trans,
                     fontsize="x-large",
                     ha="right",
                 )
@@ -353,8 +343,9 @@ def on_parameter_change(self, from_fit=False, report_success=False):
             else:
                 self.results_text.clear()
 
-            for ax in self.fig.get_axes():
-                ax.clear()
+
+            plt.clf()
+            plt.gcf().set_size_inches(self.figsize)
             self.plot_with_frame(from_fit, report_success)
             self.canvas.draw_idle()
 

From c54c2d9edb6513e286b43aa346864815f68414b3 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 12 Dec 2024 00:55:32 +0000
Subject: [PATCH 23/49] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 src/iminuit/qtwidget.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index ecdb108d..ae26b30f 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -343,7 +343,6 @@ def on_parameter_change(self, from_fit=False, report_success=False):
             else:
                 self.results_text.clear()
 
-
             plt.clf()
             plt.gcf().set_size_inches(self.figsize)
             self.plot_with_frame(from_fit, report_success)

From 22dcf94e39a32fc3cd35c65b062633f0affe6f92 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Thu, 12 Dec 2024 13:48:05 +0100
Subject: [PATCH 24/49] Removed _widget prefix

---
 src/iminuit/ipywidget.py | 5 ++---
 src/iminuit/qtwidget.py  | 5 ++---
 src/iminuit/util.py      | 2 +-
 3 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/iminuit/ipywidget.py b/src/iminuit/ipywidget.py
index f006cf01..4e531b3e 100644
--- a/src/iminuit/ipywidget.py
+++ b/src/iminuit/ipywidget.py
@@ -1,7 +1,6 @@
 """Interactive fitting widget for Jupyter notebooks."""
 
-from .util import _widget_guess_initial_step as _guess_initial_step
-from .util import _widget_make_finite as _make_finite
+from .util import _widget_guess_initial_step, _make_finite
 import warnings
 import numpy as np
 from typing import Dict, Any, Callable
@@ -149,7 +148,7 @@ class Parameter(widgets.HBox):
         def __init__(self, minuit, par):
             val = minuit.values[par]
             vmin, vmax = minuit.limits[par]
-            step = _guess_initial_step(val, vmin, vmax)
+            step = _widget_guess_initial_step(val, vmin, vmax)
             vmin2 = vmin if np.isfinite(vmin) else val - 100 * step
             vmax2 = vmax if np.isfinite(vmax) else val + 100 * step
 
diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index ae26b30f..27682422 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -1,7 +1,6 @@
 """Interactive fitting widget using PyQt6."""
 
-from .util import _widget_guess_initial_step as _guess_initial_step
-from .util import _widget_make_finite as _make_finite
+from .util import _widget_guess_initial_step, _make_finite
 import warnings
 import numpy as np
 from typing import Dict, Any, Callable
@@ -166,7 +165,7 @@ def on_fit_toggled(self):
         def reset(self, val, limits=None):
             if limits is not None:
                 vmin, vmax = limits
-                step = _guess_initial_step(val, vmin, vmax)
+                step = _widget_guess_initial_step(val, vmin, vmax)
                 self.vmin = vmin if np.isfinite(vmin) else val - 100 * step
                 self.vmax = vmax if np.isfinite(vmax) else val + 100 * step
                 with block_signals(self.tmin, self.tmax):
diff --git a/src/iminuit/util.py b/src/iminuit/util.py
index 8df75095..d2959f15 100644
--- a/src/iminuit/util.py
+++ b/src/iminuit/util.py
@@ -1686,7 +1686,7 @@ def is_positive_definite(m: ArrayLike) -> bool:
     return False
 
 
-def _widget_make_finite(x: float) -> float:
+def _make_finite(x: float) -> float:
     sign = -1 if x < 0 else 1
     if abs(x) == np.inf:
         return sign * sys.float_info.max

From 70e930a6d8fdc0e9556a0754f267eae4dcdbe86f Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Thu, 12 Dec 2024 14:09:48 +0100
Subject: [PATCH 25/49] Added run_event_loop argument

---
 src/iminuit/minuit.py   |  9 +++++----
 src/iminuit/qtwidget.py | 10 +++++-----
 tests/test_draw.py      | 12 ++++++------
 3 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/src/iminuit/minuit.py b/src/iminuit/minuit.py
index 92270c7e..f57cb63e 100644
--- a/src/iminuit/minuit.py
+++ b/src/iminuit/minuit.py
@@ -2314,6 +2314,7 @@ def interactive(
         self,
         plot: Callable = None,
         raise_on_exception=False,
+        run_event_loop=True,
         **kwargs,
     ):
         """
@@ -2321,9 +2322,7 @@ def interactive(
 
         Starts a fitting application (requires PyQt6, matplotlib) in which the
         fit is visualized and the parameters can be manipulated to find good
-        starting parameters and to debug the fit. If there is a QApplication
-        already running, the widget will be returned instead of starting the
-        application.
+        starting parameters and to debug the fit.
 
         When called in a Jupyter notebook (requires ipywidgets, IPython, matplotlib),
         a fitting widget is returned instead, which can be displayed.
@@ -2371,10 +2370,12 @@ def interactive(
         if is_jupyter:
             from iminuit.ipywidget import make_widget
 
+            return make_widget(self, plot, kwargs, raise_on_exception)
         else:
             from iminuit.qtwidget import make_widget
 
-        return make_widget(self, plot, kwargs, raise_on_exception)
+            return make_widget(self, plot, kwargs, raise_on_exception,
+                               run_event_loop)
 
     def _free_parameters(self) -> Set[str]:
         return set(mp.name for mp in self._last_state if not mp.is_fixed)
diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 27682422..a2ae2413 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -23,6 +23,7 @@ def make_widget(
     plot: Callable[..., None],
     kwargs: Dict[str, Any],
     raise_on_exception: bool,
+    run_event_loop: bool,
 ):
     """Make interactive fitting widget."""
     original_values = minuit.values[:]
@@ -367,12 +368,11 @@ def on_reset_button_clicked(self):
                 x.reset(val=minuit.values[i], limits=original_limits[i])
             self.on_parameter_change()
 
-    app = QtWidgets.QApplication.instance()
-    if app is None:
-        app = QtWidgets.QApplication([])
-        app.setApplicationName("iminuit")
+    if run_event_loop:
+        app = QtWidgets.QApplication.instance()
+        if app is None:
+            app = QtWidgets.QApplication([])
 
-    if app.applicationName() == "iminuit":
         widget = Widget()
         widget.show()
         app.exec()  # this blocks the main thread
diff --git a/tests/test_draw.py b/tests/test_draw.py
index 699fc415..9bd94e39 100644
--- a/tests/test_draw.py
+++ b/tests/test_draw.py
@@ -252,10 +252,10 @@ def assert_call(self):
     m = Minuit(cost, 1, 1)
 
     with pytest.raises(AttributeError, match="no visualize method"):
-        m.interactive(raise_on_exception=True)
+        m.interactive(raise_on_exception=True, run_event_loop=False)
 
     with plot.assert_call():
-        mw1 = m.interactive(plot)
+        mw1 = m.interactive(plot, run_event_loop=False)
     qtbot.addWidget(mw1)
     assert isinstance(mw1, PyQt6.QtWidgets.QWidget)
 
@@ -292,7 +292,7 @@ def __call__(self, a, b):
     c = Cost()
     m = Minuit(c, 0, 0)
     with plot.assert_call():
-        mw = m.interactive(raise_on_exception=True)
+        mw = m.interactive(raise_on_exception=True, run_event_loop=False)
     qtbot.addWidget(mw)
 
     # this should modify slider range
@@ -333,10 +333,10 @@ def raiser(args):
     m = Minuit(lambda x, y: 0, 0, 1)
 
     # by default do not raise
-    m.interactive(raiser)
+    m.interactive(raiser, run_event_loop=False)
 
     with pytest.raises(ValueError):
-        m.interactive(raiser, raise_on_exception=True)
+        m.interactive(raiser, raise_on_exception=True, run_event_loop=False)
 
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
@@ -375,5 +375,5 @@ def __call__(self, par):
     trace_args = TraceArgs()
     m = Minuit(cost, (1, 2))
 
-    m.interactive(trace_args)
+    m.interactive(trace_args, run_event_loop=False)
     assert trace_args.nargs > 0

From 9d7cc479f420f0225c14f1c1e7790e4b8faed2fc Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Thu, 12 Dec 2024 16:48:10 +0100
Subject: [PATCH 26/49] Changed layout

---
 src/iminuit/qtwidget.py | 26 ++++++--------------------
 1 file changed, 6 insertions(+), 20 deletions(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index a2ae2413..9d542377 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -190,7 +190,7 @@ def reset(self, val, limits=None):
     class Widget(QtWidgets.QWidget):
         def __init__(self):
             super().__init__()
-            self.resize(1200, 800)
+            self.resize(1280, 720)
             font = QtGui.QFont()
             font.setPointSize(12)
             self.setFont(font)
@@ -206,12 +206,10 @@ def __init__(self):
             plot_group.setSizePolicy(size_policy)
             plot_layout = QtWidgets.QVBoxLayout(plot_group)
             fig = plt.figure()
-            self.figsize = fig.get_size_inches()
             manager = plt.get_current_fig_manager()
             self.canvas = FigureCanvasQTAgg(fig)
             self.canvas.manager = manager
             plot_layout.addWidget(self.canvas)
-            plot_layout.addStretch()
             interactive_layout.addWidget(plot_group, 0, 0, 2, 1)
 
             button_group = QtWidgets.QGroupBox("", parent=self)
@@ -220,6 +218,7 @@ def __init__(self):
                 QtWidgets.QSizePolicy.Policy.Fixed,
             )
             button_group.setSizePolicy(size_policy)
+            button_group.setMaximumWidth(500)
             button_layout = QtWidgets.QHBoxLayout(button_group)
             self.fit_button = QtWidgets.QPushButton("Fit", parent=button_group)
             self.fit_button.setStyleSheet("background-color: #2196F3; color: white")
@@ -253,10 +252,11 @@ def __init__(self):
                 QtWidgets.QSizePolicy.Policy.MinimumExpanding,
             )
             par_scroll_area.setSizePolicy(size_policy)
+            par_scroll_area.setMaximumWidth(500)
             scroll_area_contents = QtWidgets.QWidget()
             parameter_layout = QtWidgets.QVBoxLayout(scroll_area_contents)
             par_scroll_area.setWidget(scroll_area_contents)
-            interactive_layout.addWidget(par_scroll_area, 1, 1, 2, 1)
+            interactive_layout.addWidget(par_scroll_area, 1, 1, 1, 1)
             self.parameters = []
             for par in minuit.parameters:
                 parameter = Parameter(minuit, par, self.on_parameter_change)
@@ -264,21 +264,15 @@ def __init__(self):
                 parameter_layout.addWidget(parameter)
             parameter_layout.addStretch()
 
-            results_scroll_area = QtWidgets.QScrollArea()
-            results_scroll_area.setWidgetResizable(True)
-            results_scroll_area.setSizePolicy(size_policy)
-            self.results_text = QtWidgets.QTextEdit(parent=self)
-            self.results_text.setReadOnly(True)
-            results_scroll_area.setWidget(self.results_text)
-            interactive_layout.addWidget(results_scroll_area, 2, 0, 1, 1)
-
             self.plot_with_frame(from_fit=False, report_success=False)
 
         def plot_with_frame(self, from_fit, report_success):
             trans = plt.gca().transAxes
             try:
                 with warnings.catch_warnings():
+                    fig_size = plt.gcf().get_size_inches()
                     minuit.visualize(plot, **kwargs)
+                    plt.gcf().set_size_inches(fig_size)
             except Exception:
                 if raise_on_exception:
                     raise
@@ -334,17 +328,9 @@ def on_parameter_change(self, from_fit=False, report_success=False):
                     minuit.fixed[i] = not x.fit.isChecked()
                 from_fit = True
                 report_success = self.do_fit(plot=False)
-                self.results_text.clear()
-                self.results_text.setHtml(minuit._repr_html_())
                 minuit.fixed = saved
-            elif from_fit:
-                self.results_text.clear()
-                self.results_text.setHtml(minuit._repr_html_())
-            else:
-                self.results_text.clear()
 
             plt.clf()
-            plt.gcf().set_size_inches(self.figsize)
             self.plot_with_frame(from_fit, report_success)
             self.canvas.draw_idle()
 

From 811b27b950fda0993d1e716fcdd8d1cd0ecb395e Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 12 Dec 2024 15:57:44 +0000
Subject: [PATCH 27/49] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 src/iminuit/minuit.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/iminuit/minuit.py b/src/iminuit/minuit.py
index f57cb63e..cbc24164 100644
--- a/src/iminuit/minuit.py
+++ b/src/iminuit/minuit.py
@@ -2374,8 +2374,7 @@ def interactive(
         else:
             from iminuit.qtwidget import make_widget
 
-            return make_widget(self, plot, kwargs, raise_on_exception,
-                               run_event_loop)
+            return make_widget(self, plot, kwargs, raise_on_exception, run_event_loop)
 
     def _free_parameters(self) -> Set[str]:
         return set(mp.name for mp in self._last_state if not mp.is_fixed)

From 30a11842607ecb5fccc5ded2cbe4434bcb5f97ac Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Fri, 13 Dec 2024 19:45:36 +0100
Subject: [PATCH 28/49] Added is_jupyter

---
 src/iminuit/util.py              | 12 ++++++++++++
 tests/test_without_ipywidgets.py |  2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/iminuit/util.py b/src/iminuit/util.py
index d2959f15..3df7a3ea 100644
--- a/src/iminuit/util.py
+++ b/src/iminuit/util.py
@@ -1686,6 +1686,18 @@ def is_positive_definite(m: ArrayLike) -> bool:
     return False
 
 
+def is_jupyter() -> bool:
+    try:
+         from IPython import get_ipython
+         ip = get_ipython()
+         return ip.has_trait('kernel')
+    except ImportError:
+         return False
+    except AttributeError:
+         return False
+    return False
+
+
 def _make_finite(x: float) -> float:
     sign = -1 if x < 0 else 1
     if abs(x) == np.inf:
diff --git a/tests/test_without_ipywidgets.py b/tests/test_without_ipywidgets.py
index 7e2df799..48445901 100644
--- a/tests/test_without_ipywidgets.py
+++ b/tests/test_without_ipywidgets.py
@@ -14,5 +14,5 @@ def test_interactive(mock_ipython):
     iminuit.Minuit(cost, 1).interactive()
 
     with hide_modules("ipywidgets", reload="iminuit.ipywidget"):
-        with pytest.raises(ModuleNotFoundError, match="Please install"):
+        with pytest.raises(ModuleNotFoundError, match="Please install ipywidgets"):
             iminuit.Minuit(cost, 1).interactive()

From 6e56da0ae4407138a9e9b931e62fcf6813608487 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Fri, 13 Dec 2024 19:47:10 +0100
Subject: [PATCH 29/49] Moved run_event_loop to make_widget

---
 src/iminuit/qtwidget.py     |  2 +-
 tests/conftest.py           |  7 +++++--
 tests/test_draw.py          | 20 ++++++++++++--------
 tests/test_without_pyqt6.py |  2 +-
 4 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 9d542377..6732e959 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -23,7 +23,7 @@ def make_widget(
     plot: Callable[..., None],
     kwargs: Dict[str, Any],
     raise_on_exception: bool,
-    run_event_loop: bool,
+    run_event_loop: bool = True,
 ):
     """Make interactive fitting widget."""
     original_values = minuit.values[:]
diff --git a/tests/conftest.py b/tests/conftest.py
index eb4b20fa..bbce2d19 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -6,7 +6,10 @@
 def mock_ipython():
     with patch("IPython.get_ipython") as mock_get_ipython:
         mock_shell = MagicMock()
-        mock_shell.__class__.__name__ = "ZMQInteractiveShell"
-        mock_shell.config = {"IPKernelApp": True}
+
+        def has_trait(name):
+            return True
+
+        mock_shell.has_trait.side_effect = has_trait
         mock_get_ipython.return_value = mock_shell
         yield
diff --git a/tests/test_draw.py b/tests/test_draw.py
index 9bd94e39..6f8aa062 100644
--- a/tests/test_draw.py
+++ b/tests/test_draw.py
@@ -15,6 +15,13 @@ def f1(x, y):
     return (1 - x) ** 2 + np.exp((y - 1) ** 2)
 
 
+def qtinteractive(m, plot=None, raise_on_exception=False, **kwargs):
+    from iminuit.qtwidget import make_widget
+
+    return make_widget(m, plot, kwargs, raise_on_exception,
+                       run_event_loop=False)
+
+
 @pytest.fixture
 def minuit():
     m = Minuit(f1, x=0, y=0)
@@ -251,11 +258,8 @@ def assert_call(self):
 
     m = Minuit(cost, 1, 1)
 
-    with pytest.raises(AttributeError, match="no visualize method"):
-        m.interactive(raise_on_exception=True, run_event_loop=False)
-
     with plot.assert_call():
-        mw1 = m.interactive(plot, run_event_loop=False)
+        mw1 = qtinteractive(m, plot)
     qtbot.addWidget(mw1)
     assert isinstance(mw1, PyQt6.QtWidgets.QWidget)
 
@@ -292,7 +296,7 @@ def __call__(self, a, b):
     c = Cost()
     m = Minuit(c, 0, 0)
     with plot.assert_call():
-        mw = m.interactive(raise_on_exception=True, run_event_loop=False)
+        mw = qtinteractive(m, raise_on_exception=True)
     qtbot.addWidget(mw)
 
     # this should modify slider range
@@ -333,10 +337,10 @@ def raiser(args):
     m = Minuit(lambda x, y: 0, 0, 1)
 
     # by default do not raise
-    m.interactive(raiser, run_event_loop=False)
+    qtinteractive(m, raiser)
 
     with pytest.raises(ValueError):
-        m.interactive(raiser, raise_on_exception=True, run_event_loop=False)
+        qtinteractive(m, raiser, raise_on_exception=True)
 
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
@@ -375,5 +379,5 @@ def __call__(self, par):
     trace_args = TraceArgs()
     m = Minuit(cost, (1, 2))
 
-    m.interactive(trace_args, run_event_loop=False)
+    qtinteractive(m, trace_args)
     assert trace_args.nargs > 0
diff --git a/tests/test_without_pyqt6.py b/tests/test_without_pyqt6.py
index 0c746487..3886b2a8 100644
--- a/tests/test_without_pyqt6.py
+++ b/tests/test_without_pyqt6.py
@@ -12,5 +12,5 @@ def test_interactive(qtbot):
     cost = LeastSquares([1.1, 2.2], [3.3, 4.4], 1, lambda x, a: a * x)
 
     with hide_modules("PyQt6", reload="iminuit.qtwidget"):
-        with pytest.raises(ModuleNotFoundError, match="Please install"):
+        with pytest.raises(ModuleNotFoundError, match="Please install PyQt6"):
             iminuit.Minuit(cost, 1).interactive()

From 5c866aeccdf90ec39cffc5f6becddeaaa063ffe8 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Fri, 13 Dec 2024 19:48:43 +0100
Subject: [PATCH 30/49] Use is_jupyter from util and remove run_event_loop

---
 src/iminuit/minuit.py | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/src/iminuit/minuit.py b/src/iminuit/minuit.py
index cbc24164..54ec4dcb 100644
--- a/src/iminuit/minuit.py
+++ b/src/iminuit/minuit.py
@@ -2314,7 +2314,6 @@ def interactive(
         self,
         plot: Callable = None,
         raise_on_exception=False,
-        run_event_loop=True,
         **kwargs,
     ):
         """
@@ -2352,29 +2351,15 @@ def interactive(
         --------
         Minuit.visualize
         """
-        try:
-            from IPython import get_ipython
-
-            if (
-                get_ipython().__class__.__name__ == "ZMQInteractiveShell"
-                and "IPKernelApp" in get_ipython().config
-            ):
-                is_jupyter = True
-            else:
-                is_jupyter = False
-        except Exception:
-            is_jupyter = False
-
         plot = self._visualize(plot)
 
-        if is_jupyter:
+        if mutil.is_jupyter():
             from iminuit.ipywidget import make_widget
 
-            return make_widget(self, plot, kwargs, raise_on_exception)
         else:
             from iminuit.qtwidget import make_widget
 
-            return make_widget(self, plot, kwargs, raise_on_exception, run_event_loop)
+        return make_widget(self, plot, kwargs, raise_on_exception)
 
     def _free_parameters(self) -> Set[str]:
         return set(mp.name for mp in self._last_state if not mp.is_fixed)

From 0ec29697a9f9d3acb8cec3c77b015f89b4b4f94c Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Fri, 13 Dec 2024 18:49:11 +0000
Subject: [PATCH 31/49] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 src/iminuit/util.py | 11 ++++++-----
 tests/test_draw.py  |  3 +--
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/iminuit/util.py b/src/iminuit/util.py
index 3df7a3ea..ff18934d 100644
--- a/src/iminuit/util.py
+++ b/src/iminuit/util.py
@@ -1688,13 +1688,14 @@ def is_positive_definite(m: ArrayLike) -> bool:
 
 def is_jupyter() -> bool:
     try:
-         from IPython import get_ipython
-         ip = get_ipython()
-         return ip.has_trait('kernel')
+        from IPython import get_ipython
+
+        ip = get_ipython()
+        return ip.has_trait("kernel")
     except ImportError:
-         return False
+        return False
     except AttributeError:
-         return False
+        return False
     return False
 
 
diff --git a/tests/test_draw.py b/tests/test_draw.py
index 6f8aa062..9442a850 100644
--- a/tests/test_draw.py
+++ b/tests/test_draw.py
@@ -18,8 +18,7 @@ def f1(x, y):
 def qtinteractive(m, plot=None, raise_on_exception=False, **kwargs):
     from iminuit.qtwidget import make_widget
 
-    return make_widget(m, plot, kwargs, raise_on_exception,
-                       run_event_loop=False)
+    return make_widget(m, plot, kwargs, raise_on_exception, run_event_loop=False)
 
 
 @pytest.fixture

From f034929bffd078ddfb1448640ee92a0b2f52d425 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Fri, 13 Dec 2024 20:26:25 +0100
Subject: [PATCH 32/49] Added fmin display to qtwidget

---
 src/iminuit/qtwidget.py | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 6732e959..d4ae682c 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -256,7 +256,7 @@ def __init__(self):
             scroll_area_contents = QtWidgets.QWidget()
             parameter_layout = QtWidgets.QVBoxLayout(scroll_area_contents)
             par_scroll_area.setWidget(scroll_area_contents)
-            interactive_layout.addWidget(par_scroll_area, 1, 1, 1, 1)
+            interactive_layout.addWidget(par_scroll_area, 1, 1, 2, 1)
             self.parameters = []
             for par in minuit.parameters:
                 parameter = Parameter(minuit, par, self.on_parameter_change)
@@ -264,6 +264,12 @@ def __init__(self):
                 parameter_layout.addWidget(parameter)
             parameter_layout.addStretch()
 
+            self.results_text = QtWidgets.QTextEdit(parent=self)
+            self.results_text.setReadOnly(True)
+            self.results_text.setSizePolicy(size_policy)
+            self.results_text.setMaximumHeight(144)
+            interactive_layout.addWidget(self.results_text, 2, 0, 1, 1)
+
             self.plot_with_frame(from_fit=False, report_success=False)
 
         def plot_with_frame(self, from_fit, report_success):
@@ -330,6 +336,12 @@ def on_parameter_change(self, from_fit=False, report_success=False):
                 report_success = self.do_fit(plot=False)
                 minuit.fixed = saved
 
+            if from_fit:
+                self.results_text.clear()
+                self.results_text.setHtml(f"<div style='text-align: center;'>{minuit.fmin._repr_html_()}</div>")
+            else:
+                self.results_text.clear()
+
             plt.clf()
             self.plot_with_frame(from_fit, report_success)
             self.canvas.draw_idle()

From 7f873eaf750467b990c0f16671439de07e5bb40c Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Fri, 13 Dec 2024 19:27:25 +0000
Subject: [PATCH 33/49] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 src/iminuit/qtwidget.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index d4ae682c..94897070 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -338,7 +338,9 @@ def on_parameter_change(self, from_fit=False, report_success=False):
 
             if from_fit:
                 self.results_text.clear()
-                self.results_text.setHtml(f"<div style='text-align: center;'>{minuit.fmin._repr_html_()}</div>")
+                self.results_text.setHtml(
+                    f"<div style='text-align: center;'>{minuit.fmin._repr_html_()}</div>"
+                )
             else:
                 self.results_text.clear()
 

From 24ccc77eccbc528fec87a38353d8f3d16476d410 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone97@gmail.com>
Date: Fri, 13 Dec 2024 20:32:04 +0100
Subject: [PATCH 34/49] Removed success message

---
 src/iminuit/qtwidget.py | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 94897070..b4ae1759 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -306,14 +306,12 @@ def plot_with_frame(self, from_fit, report_success):
                 fontsize="x-large",
             )
             if from_fit and report_success:
-                plt.text(
-                    0.95,
-                    1.05,
-                    f"{'success' if minuit.valid and minuit.accurate else 'FAILURE'}",
-                    transform=trans,
-                    fontsize="x-large",
-                    ha="right",
+                self.results_text.clear()
+                self.results_text.setHtml(
+                    f"<div style='text-align: center;'>{minuit.fmin._repr_html_()}</div>"
                 )
+            else:
+                self.results_text.clear()
 
         def fit(self):
             if self.algo_choice.currentText() == "Migrad":
@@ -336,14 +334,6 @@ def on_parameter_change(self, from_fit=False, report_success=False):
                 report_success = self.do_fit(plot=False)
                 minuit.fixed = saved
 
-            if from_fit:
-                self.results_text.clear()
-                self.results_text.setHtml(
-                    f"<div style='text-align: center;'>{minuit.fmin._repr_html_()}</div>"
-                )
-            else:
-                self.results_text.clear()
-
             plt.clf()
             self.plot_with_frame(from_fit, report_success)
             self.canvas.draw_idle()

From 2fda76737dba484a3b1c250c1c69b331099f276d Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Mon, 16 Dec 2024 20:37:59 +0100
Subject: [PATCH 35/49] Fixed importskips

---
 tests/test_draw.py          | 249 ------------------------------------
 tests/test_ipywidget.py     | 129 +++++++++++++++++++
 tests/test_qtwidget.py      | 126 ++++++++++++++++++
 tests/test_without_pyqt6.py |   4 +-
 4 files changed, 256 insertions(+), 252 deletions(-)
 create mode 100644 tests/test_ipywidget.py
 create mode 100644 tests/test_qtwidget.py

diff --git a/tests/test_draw.py b/tests/test_draw.py
index 9442a850..9cd3ad5f 100644
--- a/tests/test_draw.py
+++ b/tests/test_draw.py
@@ -2,8 +2,6 @@
 from iminuit import Minuit
 from pathlib import Path
 import numpy as np
-from numpy.testing import assert_allclose
-import contextlib
 
 mpl = pytest.importorskip("matplotlib")
 plt = pytest.importorskip("matplotlib.pyplot")
@@ -15,12 +13,6 @@ def f1(x, y):
     return (1 - x) ** 2 + np.exp((y - 1) ** 2)
 
 
-def qtinteractive(m, plot=None, raise_on_exception=False, **kwargs):
-    from iminuit.qtwidget import make_widget
-
-    return make_widget(m, plot, kwargs, raise_on_exception, run_event_loop=False)
-
-
 @pytest.fixture
 def minuit():
     m = Minuit(f1, x=0, y=0)
@@ -139,244 +131,3 @@ def test_mnmatrix_7(fig):
     m = Minuit(lambda x: abs(x) ** 2 + x**4 + 10 * x, x=0)
     m.migrad()
     m.draw_mnmatrix(cl=[1, 3])
-
-
-@pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_ipywidgets(mock_ipython):
-    ipywidgets = pytest.importorskip("ipywidgets")
-
-    def cost(a, b):
-        return a**2 + b**2
-
-    class Plot:
-        def __init__(self):
-            self.called = False
-            self.raises = False
-
-        def __call__(self, args):
-            self.called = True
-            if self.raises:
-                raise ValueError("foo")
-
-        @contextlib.contextmanager
-        def assert_call(self):
-            self.called = False
-            yield
-            assert self.called
-
-    plot = Plot()
-
-    m = Minuit(cost, 1, 1)
-
-    with pytest.raises(AttributeError, match="no visualize method"):
-        m.interactive(raise_on_exception=True)
-
-    with plot.assert_call():
-        out1 = m.interactive(plot)
-    assert isinstance(out1, ipywidgets.HBox)
-
-    # manipulate state to also check this code
-    ui = out1.children[1]
-    header, parameters = ui.children
-    fit_button, update_button, reset_button, algo_select = header.children
-    with plot.assert_call():
-        fit_button.click()
-    assert_allclose(m.values, (0, 0), atol=1e-5)
-    with plot.assert_call():
-        reset_button.click()
-    assert_allclose(m.values, (1, 1), atol=1e-5)
-
-    algo_select.value = "Scipy"
-    with plot.assert_call():
-        fit_button.click()
-
-    algo_select.value = "Simplex"
-    with plot.assert_call():
-        fit_button.click()
-
-    update_button.value = False
-    with plot.assert_call():
-        # because of implementation details, we have to trigger the slider several times
-        for i in range(5):
-            parameters.children[0].slider.value = i  # change first slider
-    parameters.children[0].fix.value = True
-    with plot.assert_call():
-        parameters.children[0].fit.value = True
-
-    class Cost:
-        def visualize(self, args):
-            return plot(args)
-
-        def __call__(self, a, b):
-            return (a - 100) ** 2 + (b + 100) ** 2
-
-    c = Cost()
-    m = Minuit(c, 0, 0)
-    with plot.assert_call():
-        out = m.interactive(raise_on_exception=True)
-
-    # this should modify slider range
-    ui = out.children[1]
-    header, parameters = ui.children
-    fit_button, update_button, reset_button, algo_select = header.children
-    assert parameters.children[0].slider.max == 1
-    assert parameters.children[1].slider.min == -1
-    with plot.assert_call():
-        fit_button.click()
-    assert_allclose(m.values, (100, -100), atol=1e-5)
-    # this should trigger an exception
-    plot.raises = True
-    with plot.assert_call():
-        fit_button.click()
-
-
-@pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_pyqt6(qtbot):
-    PyQt6 = pytest.importorskip("PyQt6")
-
-    def cost(a, b):
-        return a**2 + b**2
-
-    class Plot:
-        def __init__(self):
-            self.called = False
-            self.raises = False
-
-        def __call__(self, args):
-            self.called = True
-            if self.raises:
-                raise ValueError("foo")
-
-        @contextlib.contextmanager
-        def assert_call(self):
-            self.called = False
-            yield
-            assert self.called
-
-    plot = Plot()
-
-    m = Minuit(cost, 1, 1)
-
-    with plot.assert_call():
-        mw1 = qtinteractive(m, plot)
-    qtbot.addWidget(mw1)
-    assert isinstance(mw1, PyQt6.QtWidgets.QWidget)
-
-    # manipulate state to also check this code
-    with plot.assert_call():
-        mw1.fit_button.click()
-    assert_allclose(m.values, (0, 0), atol=1e-5)
-    with plot.assert_call():
-        mw1.reset_button.click()
-    assert_allclose(m.values, (1, 1), atol=1e-5)
-
-    mw1.algo_choice.setCurrentText("Scipy")
-    with plot.assert_call():
-        mw1.fit_button.click()
-
-    mw1.algo_choice.setCurrentText("Simplex")
-    with plot.assert_call():
-        mw1.fit_button.click()
-
-    mw1.update_button.click()
-    with plot.assert_call():
-        mw1.parameters[0].slider.valueChanged.emit(int(5e7))
-    mw1.parameters[0].fix.click()
-    with plot.assert_call():
-        mw1.parameters[0].fit.click()
-
-    class Cost:
-        def visualize(self, args):
-            return plot(args)
-
-        def __call__(self, a, b):
-            return (a - 100) ** 2 + (b + 100) ** 2
-
-    c = Cost()
-    m = Minuit(c, 0, 0)
-    with plot.assert_call():
-        mw = qtinteractive(m, raise_on_exception=True)
-    qtbot.addWidget(mw)
-
-    # this should modify slider range
-    assert mw.parameters[0].vmax == 1
-    assert mw.parameters[1].vmin == -1
-    with plot.assert_call():
-        mw.fit_button.click()
-    assert_allclose(m.values, (100, -100), atol=1e-5)
-    # this should trigger an exception
-    # plot.raises = True
-    # with plot.assert_call():
-    #    mw.fit_button.click()
-
-
-@pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_ipywidgets_raises(mock_ipython):
-    pytest.importorskip("ipywidgets")
-
-    def raiser(args):
-        raise ValueError
-
-    m = Minuit(lambda x, y: 0, 0, 1)
-
-    # by default do not raise
-    m.interactive(raiser)
-
-    with pytest.raises(ValueError):
-        m.interactive(raiser, raise_on_exception=True)
-
-
-@pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_pyqt6_raises(qtbot):
-    pytest.importorskip("PyQt6")
-
-    def raiser(args):
-        raise ValueError
-
-    m = Minuit(lambda x, y: 0, 0, 1)
-
-    # by default do not raise
-    qtinteractive(m, raiser)
-
-    with pytest.raises(ValueError):
-        qtinteractive(m, raiser, raise_on_exception=True)
-
-
-@pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_ipywidgets_with_array_func(mock_ipython):
-    pytest.importorskip("ipywidgets")
-
-    def cost(par):
-        return par[0] ** 2 + (par[1] / 2) ** 2
-
-    class TraceArgs:
-        nargs = 0
-
-        def __call__(self, par):
-            self.nargs = len(par)
-
-    trace_args = TraceArgs()
-    m = Minuit(cost, (1, 2))
-
-    m.interactive(trace_args)
-    assert trace_args.nargs > 0
-
-
-@pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_pyqt6_with_array_func(qtbot):
-    pytest.importorskip("PyQt6")
-
-    def cost(par):
-        return par[0] ** 2 + (par[1] / 2) ** 2
-
-    class TraceArgs:
-        nargs = 0
-
-        def __call__(self, par):
-            self.nargs = len(par)
-
-    trace_args = TraceArgs()
-    m = Minuit(cost, (1, 2))
-
-    qtinteractive(m, trace_args)
-    assert trace_args.nargs > 0
diff --git a/tests/test_ipywidget.py b/tests/test_ipywidget.py
new file mode 100644
index 00000000..5b511af5
--- /dev/null
+++ b/tests/test_ipywidget.py
@@ -0,0 +1,129 @@
+import pytest
+from iminuit import Minuit
+from numpy.testing import assert_allclose
+import contextlib
+
+mpl = pytest.importorskip("matplotlib")
+plt = pytest.importorskip("matplotlib.pyplot")
+ipywidgets = pytest.importorskip("ipywidgets")
+
+mpl.use("Agg")
+
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_interactive_ipywidgets(mock_ipython):
+    def cost(a, b):
+        return a**2 + b**2
+
+    class Plot:
+        def __init__(self):
+            self.called = False
+            self.raises = False
+
+        def __call__(self, args):
+            self.called = True
+            if self.raises:
+                raise ValueError("foo")
+
+        @contextlib.contextmanager
+        def assert_call(self):
+            self.called = False
+            yield
+            assert self.called
+
+    plot = Plot()
+
+    m = Minuit(cost, 1, 1)
+
+    with pytest.raises(AttributeError, match="no visualize method"):
+        m.interactive(raise_on_exception=True)
+
+    with plot.assert_call():
+        out1 = m.interactive(plot)
+    assert isinstance(out1, ipywidgets.HBox)
+
+    # manipulate state to also check this code
+    ui = out1.children[1]
+    header, parameters = ui.children
+    fit_button, update_button, reset_button, algo_select = header.children
+    with plot.assert_call():
+        fit_button.click()
+    assert_allclose(m.values, (0, 0), atol=1e-5)
+    with plot.assert_call():
+        reset_button.click()
+    assert_allclose(m.values, (1, 1), atol=1e-5)
+
+    algo_select.value = "Scipy"
+    with plot.assert_call():
+        fit_button.click()
+
+    algo_select.value = "Simplex"
+    with plot.assert_call():
+        fit_button.click()
+
+    update_button.value = False
+    with plot.assert_call():
+        # because of implementation details, we have to trigger the slider several times
+        for i in range(5):
+            parameters.children[0].slider.value = i  # change first slider
+    parameters.children[0].fix.value = True
+    with plot.assert_call():
+        parameters.children[0].fit.value = True
+
+    class Cost:
+        def visualize(self, args):
+            return plot(args)
+
+        def __call__(self, a, b):
+            return (a - 100) ** 2 + (b + 100) ** 2
+
+    c = Cost()
+    m = Minuit(c, 0, 0)
+    with plot.assert_call():
+        out = m.interactive(raise_on_exception=True)
+
+    # this should modify slider range
+    ui = out.children[1]
+    header, parameters = ui.children
+    fit_button, update_button, reset_button, algo_select = header.children
+    assert parameters.children[0].slider.max == 1
+    assert parameters.children[1].slider.min == -1
+    with plot.assert_call():
+        fit_button.click()
+    assert_allclose(m.values, (100, -100), atol=1e-5)
+    # this should trigger an exception
+    plot.raises = True
+    with plot.assert_call():
+        fit_button.click()
+
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_interactive_ipywidgets_raises(mock_ipython):
+    def raiser(args):
+        raise ValueError
+
+    m = Minuit(lambda x, y: 0, 0, 1)
+
+    # by default do not raise
+    m.interactive(raiser)
+
+    with pytest.raises(ValueError):
+        m.interactive(raiser, raise_on_exception=True)
+
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_interactive_ipywidgets_with_array_func(mock_ipython):
+    def cost(par):
+        return par[0] ** 2 + (par[1] / 2) ** 2
+
+    class TraceArgs:
+        nargs = 0
+
+        def __call__(self, par):
+            self.nargs = len(par)
+
+    trace_args = TraceArgs()
+    m = Minuit(cost, (1, 2))
+
+    m.interactive(trace_args)
+    assert trace_args.nargs > 0
diff --git a/tests/test_qtwidget.py b/tests/test_qtwidget.py
new file mode 100644
index 00000000..9cb28589
--- /dev/null
+++ b/tests/test_qtwidget.py
@@ -0,0 +1,126 @@
+import pytest
+from iminuit import Minuit
+from numpy.testing import assert_allclose
+import contextlib
+
+mpl = pytest.importorskip("matplotlib")
+plt = pytest.importorskip("matplotlib.pyplot")
+PyQt6 = pytest.importorskip("PyQt6")
+
+mpl.use("Agg")
+
+
+def qtinteractive(m, plot=None, raise_on_exception=False, **kwargs):
+    from iminuit.qtwidget import make_widget
+
+    return make_widget(m, plot, kwargs, raise_on_exception, run_event_loop=False)
+
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_interactive_pyqt6(qtbot):
+    def cost(a, b):
+        return a**2 + b**2
+
+    class Plot:
+        def __init__(self):
+            self.called = False
+            self.raises = False
+
+        def __call__(self, args):
+            self.called = True
+            if self.raises:
+                raise ValueError("foo")
+
+        @contextlib.contextmanager
+        def assert_call(self):
+            self.called = False
+            yield
+            assert self.called
+
+    plot = Plot()
+
+    m = Minuit(cost, 1, 1)
+
+    with plot.assert_call():
+        mw1 = qtinteractive(m, plot)
+    qtbot.addWidget(mw1)
+    assert isinstance(mw1, PyQt6.QtWidgets.QWidget)
+
+    # manipulate state to also check this code
+    with plot.assert_call():
+        mw1.fit_button.click()
+    assert_allclose(m.values, (0, 0), atol=1e-5)
+    with plot.assert_call():
+        mw1.reset_button.click()
+    assert_allclose(m.values, (1, 1), atol=1e-5)
+
+    mw1.algo_choice.setCurrentText("Scipy")
+    with plot.assert_call():
+        mw1.fit_button.click()
+
+    mw1.algo_choice.setCurrentText("Simplex")
+    with plot.assert_call():
+        mw1.fit_button.click()
+
+    mw1.update_button.click()
+    with plot.assert_call():
+        mw1.parameters[0].slider.valueChanged.emit(int(5e7))
+    mw1.parameters[0].fix.click()
+    with plot.assert_call():
+        mw1.parameters[0].fit.click()
+
+    class Cost:
+        def visualize(self, args):
+            return plot(args)
+
+        def __call__(self, a, b):
+            return (a - 100) ** 2 + (b + 100) ** 2
+
+    c = Cost()
+    m = Minuit(c, 0, 0)
+    with plot.assert_call():
+        mw = qtinteractive(m, raise_on_exception=True)
+    qtbot.addWidget(mw)
+
+    # this should modify slider range
+    assert mw.parameters[0].vmax == 1
+    assert mw.parameters[1].vmin == -1
+    with plot.assert_call():
+        mw.fit_button.click()
+    assert_allclose(m.values, (100, -100), atol=1e-5)
+    # this should trigger an exception
+    # plot.raises = True
+    # with plot.assert_call():
+    #    mw.fit_button.click()
+
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_interactive_pyqt6_raises(qtbot):
+    def raiser(args):
+        raise ValueError
+
+    m = Minuit(lambda x, y: 0, 0, 1)
+
+    # by default do not raise
+    qtinteractive(m, raiser)
+
+    with pytest.raises(ValueError):
+        qtinteractive(m, raiser, raise_on_exception=True)
+
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_interactive_pyqt6_with_array_func(qtbot):
+    def cost(par):
+        return par[0] ** 2 + (par[1] / 2) ** 2
+
+    class TraceArgs:
+        nargs = 0
+
+        def __call__(self, par):
+            self.nargs = len(par)
+
+    trace_args = TraceArgs()
+    m = Minuit(cost, (1, 2))
+
+    qtinteractive(m, trace_args)
+    assert trace_args.nargs > 0
diff --git a/tests/test_without_pyqt6.py b/tests/test_without_pyqt6.py
index 3886b2a8..84e49c2b 100644
--- a/tests/test_without_pyqt6.py
+++ b/tests/test_without_pyqt6.py
@@ -2,10 +2,8 @@
 from iminuit.cost import LeastSquares
 import pytest
 
-pytest.importorskip("PyQt6")
 
-
-def test_interactive(qtbot):
+def test_interactive():
     pytest.importorskip("matplotlib")
     import iminuit
 

From 6c5f02b0e51615954bd39188e1dcc2a36c201ba1 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Mon, 16 Dec 2024 21:10:08 +0100
Subject: [PATCH 36/49] Ruff ignore conftest.py

---
 pyproject.toml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pyproject.toml b/pyproject.toml
index ad8940da..6330a63f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -103,6 +103,7 @@ pydocstyle.convention = "numpy"
 
 [tool.ruff.lint.per-file-ignores]
 "test_*.py" = ["B", "D"]
+"conftest.py" = ["B", "D"]
 "*.ipynb" = ["D"]
 "automatic_differentiation.ipynb" = ["F821"]
 "cython.ipynb" = ["F821"]

From 63e008230091d8fc978a5d14f11e32b1b1a15a4f Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Mon, 16 Dec 2024 21:11:24 +0100
Subject: [PATCH 37/49] block_signals -> _block_signals

---
 src/iminuit/qtwidget.py | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index b4ae1759..3d0f3d86 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -117,11 +117,11 @@ def on_val_changed(self, val):
         def on_min_changed(self):
             tmin = self.tmin.value()
             if tmin >= self.vmax:
-                with block_signals(self.tmin):
+                with _block_signals(self.tmin):
                     self.tmin.setValue(self.vmin)
                 return
             self.vmin = tmin
-            with block_signals(self.slider):
+            with _block_signals(self.slider):
                 if tmin > self.val:
                     self.val = tmin
                     minuit.values[self.par] = tmin
@@ -136,11 +136,11 @@ def on_min_changed(self):
         def on_max_changed(self):
             tmax = self.tmax.value()
             if tmax <= self.tmin.value():
-                with block_signals(self.tmax):
+                with _block_signals(self.tmax):
                     self.tmax.setValue(self.vmax)
                 return
             self.vmax = tmax
-            with block_signals(self.slider):
+            with _block_signals(self.slider):
                 if tmax < self.val:
                     self.val = tmax
                     minuit.values[self.par] = tmax
@@ -169,21 +169,21 @@ def reset(self, val, limits=None):
                 step = _widget_guess_initial_step(val, vmin, vmax)
                 self.vmin = vmin if np.isfinite(vmin) else val - 100 * step
                 self.vmax = vmax if np.isfinite(vmax) else val + 100 * step
-                with block_signals(self.tmin, self.tmax):
+                with _block_signals(self.tmin, self.tmax):
                     self.tmin.setValue(self.vmin)
                     self.tmax.setValue(self.vmax)
 
             self.val = val
             if self.val < self.vmin:
                 self.vmin = self.val
-                with block_signals(self.tmin):
+                with _block_signals(self.tmin):
                     self.tmin.setValue(self.vmin)
             elif self.val > self.vmax:
                 self.vmax = self.val
-                with block_signals(self.tmax):
+                with _block_signals(self.tmax):
                     self.tmax.setValue(self.vmax)
 
-            with block_signals(self.slider):
+            with _block_signals(self.slider):
                 self.slider.setValue(self._float_to_int(self.val))
             self.value_label.setText(f"{self.val:.3g}")
 
@@ -371,7 +371,7 @@ def on_reset_button_clicked(self):
 
 
 @contextmanager
-def block_signals(*widgets):
+def _block_signals(*widgets):
     for w in widgets:
         w.blockSignals(True)
     try:

From 2d872ab9cc58717b8807e96537d4778bc19ca4ea Mon Sep 17 00:00:00 2001
From: Hans Dembinski <hans.dembinski@gmail.com>
Date: Tue, 17 Dec 2024 11:34:21 +0100
Subject: [PATCH 38/49] attempt to fix ci

---
 .github/workflows/coverage.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index e050b8c9..ae04885b 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -33,6 +33,7 @@ jobs:
       with:
         python-version: "3.12"
     - uses: astral-sh/setup-uv@v4
+    - run: sudo apt install libegl1-mesa:i386 libegl1:i386
     - run: uv pip install --system nox
     - run: nox -s cov
     - uses: AndreMiras/coveralls-python-action@develop

From 3ffd0c8f6b818a54a34889fa4896f392003925b4 Mon Sep 17 00:00:00 2001
From: Hans Dembinski <hans.dembinski@gmail.com>
Date: Tue, 17 Dec 2024 13:44:04 +0100
Subject: [PATCH 39/49] attempt to fix

---
 .github/workflows/coverage.yml | 46 ++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 22 deletions(-)

diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index ae04885b..0d7463f2 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -3,37 +3,39 @@ name: Coverage
 on:
   pull_request:
     paths-ignore:
-      - 'doc/**'
-      - '.ci/**'
-      - '*.rst'
+      - "doc/**"
+      - ".ci/**"
+      - "*.rst"
   push:
     branches:
       - main
       - develop
       - beta/*
     paths-ignore:
-      - 'doc/**'
-      - '.ci/**'
-      - '*.rst'
+      - "doc/**"
+      - ".ci/**"
+      - "*.rst"
 
 jobs:
   coverage:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
-      with:
-        submodules: true
-    - uses: hendrikmuhs/ccache-action@v1.2
-      with:
-        key: ${{ github.job }}-${{ matrix.os }}-${{ matrix.python-version }}
-        create-symlink: true
-    - uses: rui314/setup-mold@v1
-    - uses: actions/setup-python@v5
-      with:
-        python-version: "3.12"
-    - uses: astral-sh/setup-uv@v4
-    - run: sudo apt install libegl1-mesa:i386 libegl1:i386
-    - run: uv pip install --system nox
-    - run: nox -s cov
-    - uses: AndreMiras/coveralls-python-action@develop
+      - uses: jurplel/install-qt-action@v4
+        with:
+          version: "6.*"
+      - uses: actions/checkout@v4
+        with:
+          submodules: true
+      - uses: hendrikmuhs/ccache-action@v1.2
+        with:
+          key: ${{ github.job }}-${{ matrix.os }}-${{ matrix.python-version }}
+          create-symlink: true
+      - uses: rui314/setup-mold@v1
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - uses: astral-sh/setup-uv@v4
+      - run: uv pip install --system nox
+      - run: nox -s cov
+      - uses: AndreMiras/coveralls-python-action@develop

From 7ec04b20c1f9a513a2b3d847e779d07b94fd4519 Mon Sep 17 00:00:00 2001
From: Hans Dembinski <hans.dembinski@gmail.com>
Date: Tue, 17 Dec 2024 14:08:20 +0100
Subject: [PATCH 40/49] attempt to fix ci

---
 .github/workflows/coverage.yml | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index 0d7463f2..b4a62cfd 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -21,9 +21,18 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: jurplel/install-qt-action@v4
+      # install-qt-action also does setup-python
+      - name: Install Qt
+        uses: jurplel/install-qt-action@v3
         with:
-          version: "6.*"
+          aqtversion: "==3.1.*"
+          version: "6.5.3"
+          host: "linux"
+          target: "desktop"
+          arch: "gcc_64"
+      # - uses: actions/setup-python@v5
+      #   with:
+      #     python-version: "3.12"
       - uses: actions/checkout@v4
         with:
           submodules: true
@@ -32,9 +41,6 @@ jobs:
           key: ${{ github.job }}-${{ matrix.os }}-${{ matrix.python-version }}
           create-symlink: true
       - uses: rui314/setup-mold@v1
-      - uses: actions/setup-python@v5
-        with:
-          python-version: "3.12"
       - uses: astral-sh/setup-uv@v4
       - run: uv pip install --system nox
       - run: nox -s cov

From 8d50cbee1b6afba85f00c9ee31b50dbcd225b616 Mon Sep 17 00:00:00 2001
From: Hans Dembinski <hans.dembinski@gmail.com>
Date: Tue, 17 Dec 2024 14:14:01 +0100
Subject: [PATCH 41/49] attempt to fix ci

---
 .github/workflows/coverage.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index b4a62cfd..490abd83 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -26,10 +26,10 @@ jobs:
         uses: jurplel/install-qt-action@v3
         with:
           aqtversion: "==3.1.*"
-          version: "6.5.3"
+          version: "6.8.1"
           host: "linux"
           target: "desktop"
-          arch: "gcc_64"
+          arch: "linux_gcc_64"
       # - uses: actions/setup-python@v5
       #   with:
       #     python-version: "3.12"

From 17abd162c6763cd7668b802fb72bab8690e3f3d7 Mon Sep 17 00:00:00 2001
From: Hans Dembinski <hans.dembinski@gmail.com>
Date: Tue, 17 Dec 2024 14:31:14 +0100
Subject: [PATCH 42/49] attempt to fix ci

---
 noxfile.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/noxfile.py b/noxfile.py
index 3710a3f9..f6f99b27 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -67,7 +67,7 @@ def pypy(session: nox.Session) -> None:
 
 
 # Python-3.12 provides coverage info faster
-@nox.session(python="3.12", venv_backend="uv", reuse_venv=True)
+@nox.session(venv_backend="uv", reuse_venv=True)
 def cov(session: nox.Session) -> None:
     """Run covage and place in 'htmlcov' directory."""
     session.install("--only-binary=:all:", "-e.[test,doc]")

From dffbcf0398af8a5da7256fc5123626635a9ad144 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Thu, 19 Dec 2024 15:25:50 +0100
Subject: [PATCH 43/49] Added comment

---
 src/iminuit/util.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/iminuit/util.py b/src/iminuit/util.py
index ff18934d..b040a084 100644
--- a/src/iminuit/util.py
+++ b/src/iminuit/util.py
@@ -1695,6 +1695,7 @@ def is_jupyter() -> bool:
     except ImportError:
         return False
     except AttributeError:
+        # get_ipython() returns None if no InteractiveShell instance is registered.
         return False
     return False
 

From 42032322cf796b9484db2394c3379e23dd654ee2 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Thu, 19 Dec 2024 15:30:57 +0100
Subject: [PATCH 44/49] Exclude run_event_loop from cov

---
 src/iminuit/qtwidget.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index 3d0f3d86..f54e0207 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -358,7 +358,7 @@ def on_reset_button_clicked(self):
                 x.reset(val=minuit.values[i], limits=original_limits[i])
             self.on_parameter_change()
 
-    if run_event_loop:
+    if run_event_loop:  # pragma: no cover, should not be executed in tests
         app = QtWidgets.QApplication.instance()
         if app is None:
             app = QtWidgets.QApplication([])

From a8ad0dc0de40d13088cc62e58cdfdab408e31313 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Thu, 19 Dec 2024 15:53:37 +0100
Subject: [PATCH 45/49] Test both AttributeError and ImportError in is_jupyter

---
 tests/test_without_pyqt6.py | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/tests/test_without_pyqt6.py b/tests/test_without_pyqt6.py
index 84e49c2b..49345770 100644
--- a/tests/test_without_pyqt6.py
+++ b/tests/test_without_pyqt6.py
@@ -2,9 +2,11 @@
 from iminuit.cost import LeastSquares
 import pytest
 
+pytest.importorskip("matplotlib")
 
-def test_interactive():
-    pytest.importorskip("matplotlib")
+
+def test_pyqt6_interactive_with_ipython():
+    pytest.importorskip("IPython")
     import iminuit
 
     cost = LeastSquares([1.1, 2.2], [3.3, 4.4], 1, lambda x, a: a * x)
@@ -12,3 +14,13 @@ def test_interactive():
     with hide_modules("PyQt6", reload="iminuit.qtwidget"):
         with pytest.raises(ModuleNotFoundError, match="Please install PyQt6"):
             iminuit.Minuit(cost, 1).interactive()
+
+
+def test_pyqt6_interactive_without_ipython():
+    import iminuit
+
+    cost = LeastSquares([1.1, 2.2], [3.3, 4.4], 1, lambda x, a: a * x)
+
+    with hide_modules("PyQt6", "IPython", reload="iminuit.qtwidget"):
+        with pytest.raises(ModuleNotFoundError, match="Please install PyQt6"):
+            iminuit.Minuit(cost, 1).interactive()

From 594a89c8b4d557cca9a9608f6e47265c0de4e653 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Thu, 19 Dec 2024 16:53:05 +0100
Subject: [PATCH 46/49] Added tests for changing limits

---
 tests/test_qtwidget.py | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/tests/test_qtwidget.py b/tests/test_qtwidget.py
index 9cb28589..4dc89fb6 100644
--- a/tests/test_qtwidget.py
+++ b/tests/test_qtwidget.py
@@ -69,6 +69,28 @@ def assert_call(self):
     with plot.assert_call():
         mw1.parameters[0].fit.click()
 
+    # check changing of limits
+    mw1.parameters[0].fit.click()
+    mw1.parameters[0].tmin.setValue(-1)
+    mw1.parameters[0].tmax.setValue(1)
+    assert_allclose(m.limits["a"], (-1, 1), atol=1e-5)
+    with plot.assert_call():
+        mw1.parameters[0].tmin.setValue(0.5)
+    assert_allclose(m.limits["a"], (0.5, 1), atol=1e-5)
+    assert_allclose(m.values, (0.5, 0), atol=1e-5)
+    mw1.parameters[0].tmin.setValue(2)
+    assert_allclose(m.limits["a"], (0.5, 1), atol=1e-5)
+    assert_allclose(m.values, (0.5, 0), atol=1e-5)
+    mw1.parameters[0].tmin.setValue(-1)
+    with plot.assert_call():
+        mw1.parameters[0].tmax.setValue(0)
+    assert_allclose(m.limits["a"], (-1, 0), atol=1e-5)
+    assert_allclose(m.values, (0, 0), atol=1e-5)
+    mw1.parameters[0].tmax.setValue(-2)
+    assert_allclose(m.limits["a"], (-1, 0), atol=1e-5)
+    assert_allclose(m.values, (0, 0), atol=1e-5)
+
+
     class Cost:
         def visualize(self, args):
             return plot(args)

From 3167f0f595ec4f39f2981110a49570e91fc06e38 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 19 Dec 2024 16:01:18 +0000
Subject: [PATCH 47/49] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 tests/test_qtwidget.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tests/test_qtwidget.py b/tests/test_qtwidget.py
index 4dc89fb6..e9416f82 100644
--- a/tests/test_qtwidget.py
+++ b/tests/test_qtwidget.py
@@ -90,7 +90,6 @@ def assert_call(self):
     assert_allclose(m.limits["a"], (-1, 0), atol=1e-5)
     assert_allclose(m.values, (0, 0), atol=1e-5)
 
-
     class Cost:
         def visualize(self, args):
             return plot(args)

From b2f370bc3767900a99df06f1c281419de8e45ec7 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Thu, 19 Dec 2024 17:24:03 +0100
Subject: [PATCH 48/49] Cover all cases in _make_finite and
 _widget_guess_initial_step

---
 tests/test_qtwidget.py | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/tests/test_qtwidget.py b/tests/test_qtwidget.py
index e9416f82..0e3e16aa 100644
--- a/tests/test_qtwidget.py
+++ b/tests/test_qtwidget.py
@@ -70,23 +70,26 @@ def assert_call(self):
         mw1.parameters[0].fit.click()
 
     # check changing of limits
-    mw1.parameters[0].fit.click()
-    mw1.parameters[0].tmin.setValue(-1)
-    mw1.parameters[0].tmax.setValue(1)
+    m = Minuit(cost, 0, 0)
+    m.limits["a"] = (-2, 2)
+    mw2 = qtinteractive(m, plot)
+    qtbot.addWidget(mw2)
+    mw2.parameters[0].tmin.setValue(-1)
+    mw2.parameters[0].tmax.setValue(1)
     assert_allclose(m.limits["a"], (-1, 1), atol=1e-5)
     with plot.assert_call():
-        mw1.parameters[0].tmin.setValue(0.5)
+        mw2.parameters[0].tmin.setValue(0.5)
     assert_allclose(m.limits["a"], (0.5, 1), atol=1e-5)
     assert_allclose(m.values, (0.5, 0), atol=1e-5)
-    mw1.parameters[0].tmin.setValue(2)
+    mw2.parameters[0].tmin.setValue(2)
     assert_allclose(m.limits["a"], (0.5, 1), atol=1e-5)
     assert_allclose(m.values, (0.5, 0), atol=1e-5)
-    mw1.parameters[0].tmin.setValue(-1)
+    mw2.parameters[0].tmin.setValue(-1)
     with plot.assert_call():
-        mw1.parameters[0].tmax.setValue(0)
+        mw2.parameters[0].tmax.setValue(0)
     assert_allclose(m.limits["a"], (-1, 0), atol=1e-5)
     assert_allclose(m.values, (0, 0), atol=1e-5)
-    mw1.parameters[0].tmax.setValue(-2)
+    mw2.parameters[0].tmax.setValue(-2)
     assert_allclose(m.limits["a"], (-1, 0), atol=1e-5)
     assert_allclose(m.values, (0, 0), atol=1e-5)
 

From a817bc984148f61b25db8c58a59c5ac86f13c545 Mon Sep 17 00:00:00 2001
From: Adrian Peter Krone <adrian.krone@ptoton.me>
Date: Thu, 19 Dec 2024 17:47:33 +0100
Subject: [PATCH 49/49] PyQt6 -> PySide6

---
 pyproject.toml                                       |  2 +-
 src/iminuit/minuit.py                                |  2 +-
 src/iminuit/qtwidget.py                              |  6 +++---
 tests/test_qtwidget.py                               | 10 +++++-----
 ...test_without_pyqt6.py => test_without_pyside6.py} | 12 ++++++------
 5 files changed, 16 insertions(+), 16 deletions(-)
 rename tests/{test_without_pyqt6.py => test_without_pyside6.py} (69%)

diff --git a/pyproject.toml b/pyproject.toml
index 6330a63f..ca2b8d9a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -44,7 +44,7 @@ test = [
     "ipywidgets",
     # needed by ipywidgets >= 8.0.6
     "ipykernel",
-    "PyQt6",
+    "PySide6",
     "joblib",
     "jacobi",
     "matplotlib",
diff --git a/src/iminuit/minuit.py b/src/iminuit/minuit.py
index ee63b064..ff98bd4b 100644
--- a/src/iminuit/minuit.py
+++ b/src/iminuit/minuit.py
@@ -2343,7 +2343,7 @@ def interactive(
         """
         Interactive GUI for fitting.
 
-        Starts a fitting application (requires PyQt6, matplotlib) in which the
+        Starts a fitting application (requires PySide6, matplotlib) in which the
         fit is visualized and the parameters can be manipulated to find good
         starting parameters and to debug the fit.
 
diff --git a/src/iminuit/qtwidget.py b/src/iminuit/qtwidget.py
index f54e0207..ee8639af 100644
--- a/src/iminuit/qtwidget.py
+++ b/src/iminuit/qtwidget.py
@@ -1,4 +1,4 @@
-"""Interactive fitting widget using PyQt6."""
+"""Interactive fitting widget using PySide6."""
 
 from .util import _widget_guess_initial_step, _make_finite
 import warnings
@@ -7,12 +7,12 @@
 from contextlib import contextmanager
 
 try:
-    from PyQt6 import QtCore, QtGui, QtWidgets
+    from PySide6 import QtCore, QtGui, QtWidgets
     from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg
     from matplotlib import pyplot as plt
 except ModuleNotFoundError as e:
     e.msg += (
-        "\n\nPlease install PyQt6, and matplotlib to enable interactive "
+        "\n\nPlease install PySide6, and matplotlib to enable interactive "
         "outside of Jupyter notebooks."
     )
     raise
diff --git a/tests/test_qtwidget.py b/tests/test_qtwidget.py
index 0e3e16aa..b5bd3677 100644
--- a/tests/test_qtwidget.py
+++ b/tests/test_qtwidget.py
@@ -5,7 +5,7 @@
 
 mpl = pytest.importorskip("matplotlib")
 plt = pytest.importorskip("matplotlib.pyplot")
-PyQt6 = pytest.importorskip("PyQt6")
+PySide6 = pytest.importorskip("PySide6")
 
 mpl.use("Agg")
 
@@ -17,7 +17,7 @@ def qtinteractive(m, plot=None, raise_on_exception=False, **kwargs):
 
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_pyqt6(qtbot):
+def test_interactive_pyside6(qtbot):
     def cost(a, b):
         return a**2 + b**2
 
@@ -44,7 +44,7 @@ def assert_call(self):
     with plot.assert_call():
         mw1 = qtinteractive(m, plot)
     qtbot.addWidget(mw1)
-    assert isinstance(mw1, PyQt6.QtWidgets.QWidget)
+    assert isinstance(mw1, PySide6.QtWidgets.QWidget)
 
     # manipulate state to also check this code
     with plot.assert_call():
@@ -119,7 +119,7 @@ def __call__(self, a, b):
 
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_pyqt6_raises(qtbot):
+def test_interactive_pyside6_raises(qtbot):
     def raiser(args):
         raise ValueError
 
@@ -133,7 +133,7 @@ def raiser(args):
 
 
 @pytest.mark.filterwarnings("ignore::DeprecationWarning")
-def test_interactive_pyqt6_with_array_func(qtbot):
+def test_interactive_pyside6_with_array_func(qtbot):
     def cost(par):
         return par[0] ** 2 + (par[1] / 2) ** 2
 
diff --git a/tests/test_without_pyqt6.py b/tests/test_without_pyside6.py
similarity index 69%
rename from tests/test_without_pyqt6.py
rename to tests/test_without_pyside6.py
index 49345770..db048811 100644
--- a/tests/test_without_pyqt6.py
+++ b/tests/test_without_pyside6.py
@@ -5,22 +5,22 @@
 pytest.importorskip("matplotlib")
 
 
-def test_pyqt6_interactive_with_ipython():
+def test_pyside6_interactive_with_ipython():
     pytest.importorskip("IPython")
     import iminuit
 
     cost = LeastSquares([1.1, 2.2], [3.3, 4.4], 1, lambda x, a: a * x)
 
-    with hide_modules("PyQt6", reload="iminuit.qtwidget"):
-        with pytest.raises(ModuleNotFoundError, match="Please install PyQt6"):
+    with hide_modules("PySide6", reload="iminuit.qtwidget"):
+        with pytest.raises(ModuleNotFoundError, match="Please install PySide6"):
             iminuit.Minuit(cost, 1).interactive()
 
 
-def test_pyqt6_interactive_without_ipython():
+def test_pyside6_interactive_without_ipython():
     import iminuit
 
     cost = LeastSquares([1.1, 2.2], [3.3, 4.4], 1, lambda x, a: a * x)
 
-    with hide_modules("PyQt6", "IPython", reload="iminuit.qtwidget"):
-        with pytest.raises(ModuleNotFoundError, match="Please install PyQt6"):
+    with hide_modules("PySide6", "IPython", reload="iminuit.qtwidget"):
+        with pytest.raises(ModuleNotFoundError, match="Please install PySide6"):
             iminuit.Minuit(cost, 1).interactive()