Saves and Restores the Focus Owner Before and After a Dialog is Shown (…

…#39)

* Saves and Restores the Focus Owner Before and After a Dialog is Shown

This is probably related to `DialogSupportingSwingPanel` and sometimes causes a crash on Linux when:
 * Click in a code panel to set focus
 * Open Settings
 * Close Settings
 * Press any key

 I'm pretty sure this fixes it. I was able to repro very frequently before, and now I can't repro.

 That said, I was never able to get a 100% repro case.

* Remove print statement

---------

Co-authored-by: Romain Guy <[email protected]>

src/jvmMain/kotlin/dev/romainguy/kotlin/explorer/DialogState.kt

@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2023 Romain Guy
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dev.romainguy.kotlin.explorer
+
+import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.mutableStateOf
+import java.awt.Component
+import javax.swing.FocusManager
+
+/**
+ * A [MutableState]<[Boolean]> that saves and restores the focus owner before and after a dialog is shown.
+ *
+ * This is probably related to [DialogSupportingSwingPanel] and sometimes causes a crash on Linux when:
+ * * Click in a code panel to set focus
+ * * Open Settings
+ * * Close Settings
+ * * Press any key
+ *
+ * TODO: Remove all this code
+ * See https://github.com/JetBrains/compose-multiplatform-core/pull/915
+ */
+class DialogState(initial: Boolean) : MutableState<Boolean> {
+    private var state = mutableStateOf(initial)
+    private var focusOwner: Component? = null
+    override var value: Boolean
+        get() = state.value
+        set(value) {
+            if (value) {
+                focusOwner = FocusManager.getCurrentManager().focusOwner
+            } else {
+                focusOwner?.requestFocus()
+            }
+            state.value = value
+        }
+
+    override fun component1() = state.component1()
+
+    override fun component2() = state.component2()
+}

src/jvmMain/kotlin/dev/romainguy/kotlin/explorer/KotlinExplorer.kt

@@ -127,7 +127,7 @@ private fun FrameWindowScope.KotlinExplorer(
     val codeTextAreas = listOf(byteCodeTextArea, dexTextArea, oatTextArea)
 
     val findDialog = remember { FindDialog(window, searchListener).apply { searchContext.searchWrap = true } }
-    var showSettings by remember { mutableStateOf(!explorerState.toolPaths.isValid) }
+    var showSettings by remember { DialogState(!explorerState.toolPaths.isValid) }
 
     val sourcePanel: @Composable () -> Unit = { SourcePanel(sourceTextArea, explorerState, showSettings) }
     val byteCodePanel: @Composable () -> Unit = { TextPanel("Byte Code", byteCodeTextArea, explorerState, showSettings) }