Fix or try fixing JS DOM display issues in BoxWithConstraints, `com…

….huanshankeji.compose.material2.ext.TopAppBarScaffold`, and `com.huanshankeji.compose.material3.lazy.ext.List`

1. fix the bug that a direct child with `fillMaxSizeStretch` (CSS `stretch`) doesn't work properly in the `content` of `TopAppBarScaffold` that it's sometimes rendered with the height 0

   This can be triggered either when used with `BoxWithConstraints` or by changing the window size, and the expected correct behavior can be restored by inspecting the element. The 0-height issue in `BoxWithConstraints` turns out to be caused by this. The root cause for this is that `fillMaxSizeStretch`/`stretch` seems buggy when used directly in a `position: absolute` parent. This may be a bug in the browser engines used. Consider reporting this.

1. try fixing an issue that a scrollable `List` with many items take all the space of a parent `Column` and hide components in the same `Column` before it, but fail

common/src/commonMain/kotlin/com/huanshankeji/compose/foundation/Scroll.kt

@@ -2,6 +2,7 @@ package com.huanshankeji.compose.foundation
 
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.Stable
+import com.huanshankeji.compose.ExperimentalApi
 import com.huanshankeji.compose.foundation.layout.BoxScope
 import com.huanshankeji.compose.ui.Alignment
 import com.huanshankeji.compose.ui.Modifier
@@ -24,6 +25,7 @@ See https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollTop.
  * it applies to the target as a whole on `androidx` targets, but applies to its content on JS DOM.
  * For consistency on different platforms, [VerticalScrollBox] is recommended over this modifier.
  */
+@ExperimentalApi
 expect fun Modifier.verticalScroll(
     state: ScrollState
     /*
@@ -37,6 +39,7 @@ expect fun Modifier.verticalScroll(
  * For consistency on different platforms, [HorizontalScrollBox] is recommended over this modifier.
  * @see verticalScroll
  */
+@ExperimentalApi
 expect fun Modifier.horizontalScroll(state: ScrollState): Modifier
 
 @Composable

common/src/commonMain/kotlin/com/huanshankeji/compose/ui/unit/ext/DpOrPercentage.kt

@@ -1,8 +1,10 @@
 package com.huanshankeji.compose.ui.unit.ext
 
 import androidx.annotation.IntRange
+import com.huanshankeji.compose.ExperimentalApi
 
 // not used yet
+@ExperimentalApi
 sealed class DpOrPercentage {
     class Dp(val dp: androidx.compose.ui.unit.Dp) : DpOrPercentage()
     class Percentage(@IntRange(0, 100) val percentage: Int) : DpOrPercentage()

common/src/jsMain/kotlin/com/huanshankeji/compose/foundation/Scroll.js.kt

@@ -34,7 +34,6 @@ actual object ScrollState
 actual fun Modifier.verticalScroll(state: ScrollState): Modifier =
     platformModify { verticalScroll() }
 
-
 actual fun Modifier.horizontalScroll(state: ScrollState): Modifier =
     platformModify { horizontalScroll() }
 

common/src/jsMain/kotlin/com/huanshankeji/compose/foundation/layout/ext/BoxWithConstraints.js.kt

@@ -18,36 +18,30 @@ actual fun BoxWithConstraints(
     contentAlignment: Alignment,
     content: @Composable BoxWithConstraintsScope.() -> Unit
 ) {
+    // `DpClientSize.unspecified` instead of null can be used by default to prevent the content from not rendering when `clientSize` is not set
     var clientSize by remember { mutableStateOf<ClientSize?>(null) }
     // `DivBox` doesn't work here either, so it should not be Kobweb's problem.
     Box(
         Modifier.fillMaxSizeStretch()
             .platformModify {
                 attrsModifier {
                     ref {
-                        //clientSize = ClientSize(it.clientWidth, it.clientHeight) // Adding this doesn't make a difference to solve the issue below.
+                        //console.log("Initial client size: ${it.clientWidth}, ${it.clientHeight}")
+                        // Adding this doesn't make a difference in solving the issue below.
+                        //clientSize = ClientSize(it.clientWidth, it.clientHeight)
                         val resizeObserver = ResizeObserver { entries, _ ->
-                            val element = entries.first().target
+                            val element = entries.single().target
 
                             /*
                             console.log("width: ${element.clientWidth}, height: ${element.clientHeight}")
                             console.log(entries.first().contentBoxSize.first())
                             console.log(entries.first().borderBoxSize.first())
-                            console.log(entries.first().devicePixelContentBoxSize.first())
+                            console.log(entries.first().devicePixelContentBoxSize.first()) // If there is zoom this one is different from the 2 above.
                             */
 
-                            /* FIXME The height is sometimes 0 when resizing,
-                                a non-zero size (as filtered through below) is not observed in time,
-                                and sometimes a child element doesn't show,
-                                until it's inspected with the Chrome Dev Tools.
-                            I don't know whether this is a browser bug or a bug in our implementation.
-                            Therefore, the 0 size changes are filtered out.
-                            Uncomment the commented `console.log` debug code above to debug this further. */
                             with(element) {
-                                if (clientWidth != 0 && clientHeight != 0) {
-                                    //console.log("width: ${element.clientWidth}, height: ${element.clientHeight}")
-                                    clientSize = ClientSize(clientWidth, clientHeight)
-                                }
+                                //console.log("width: $clientWidth, height: $clientHeight")
+                                clientSize = ClientSize(clientWidth, clientHeight)
                             }
                         }
                         resizeObserver.observe(it)
@@ -78,3 +72,13 @@ class BoxWithConstraintsScopeImpl(
 ) : BoxWithConstraintsScope
 
 private class ClientSize(val clientWidth: Int, val clientHeight: Int)
+
+// removed if not used
+/**
+ * Made in [Dp] so [Dp.Unspecified] can be used.
+ */
+private class DpClientSize(val clientWidth: Dp, val clientHeight: Dp) {
+    companion object {
+        val unspecified = DpClientSize(Dp.Unspecified, Dp.Unspecified)
+    }
+}

material2/src/jsMain/kotlin/com/huanshankeji/compose/material2/ext/TopAppBarScaffold.js.kt

@@ -121,6 +121,8 @@ actual fun TopAppBarScaffold(
             actions,
             Modifier.weight(1f).fillMaxWidthStretch()
         ) {
+            // This part has a lot of nested `Div`s but works. Do not change unless you are sure that expected behavior is not broken.
+
             // The content gets hidden behind the top app bar if this div is not added.
             Div({
                 style {
@@ -134,9 +136,16 @@ actual fun TopAppBarScaffold(
                         //overflow(Overflow.Auto) // This seems not needed. TODO remove if confirmed to be not needed
                     }
                 }) {
-                    // see `ScaffoldLayoutWithMeasureFix`
-                    val innerPadding = PaddingValues()
-                    content(innerPadding)
+                    // This nested `Div` is here so that a child using `fillMaxSizeStretch` works properly. `fillMaxSizeStretch` seems buggy when used directly in the `position: absolute` parent.
+                    Div({
+                        style {
+                            height(100.percent)
+                        }
+                    }) {
+                        // see `ScaffoldLayoutWithMeasureFix`
+                        val innerPadding = PaddingValues()
+                        content(innerPadding)
+                    }
                 }
 
                 floatingActionButton?.let { fabWithPosition(it) }

material3/src/jsMain/kotlin/com/huanshankeji/compose/material3/lazy/ext/List.js.kt

@@ -90,6 +90,12 @@ actual class ListScope(val mdListScope: MdListScope) {
 
 actual class ItemScope(val mdListItemScope: MdListItemScope)
 
+/*
+@Composable
+fun PrimitiveList() =
+    TODO() as Unit
+*/
+
 @Composable
 actual fun List(
     modifier: Modifier,