Use ResizeObserver to react to size changes on JS DOM in BoxWithConstraints

See the added FIXME for the reason why it doesn't work

Author: ShreckYe

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

@@ -7,6 +7,7 @@ import com.huanshankeji.compose.foundation.ExperimentalFoundationApi
 import com.huanshankeji.compose.foundation.layout.Box
 import com.huanshankeji.compose.ui.Alignment
 import com.huanshankeji.compose.ui.Modifier
+import com.varabyte.kobweb.browser.dom.observers.ResizeObserver
 import com.varabyte.kobweb.compose.foundation.layout.BoxScope
 import com.varabyte.kobweb.compose.ui.attrsModifier
 
@@ -19,14 +20,45 @@ actual fun BoxWithConstraints(
 ) {
     var clientSize by remember { mutableStateOf<ClientSize?>(null) }
     Box(
-        Modifier.platformModify {
-            attrsModifier {
-                ref {
-                    clientSize = ClientSize(it.clientWidth, it.clientHeight)
-                    onDispose { clientSize = null }
+        Modifier.fillMaxSizeStretch()
+            .platformModify {
+                attrsModifier {
+                    ref {
+                        //clientSize = ClientSize(it.clientWidth, it.clientHeight) // Adding this doesn't make a difference to solve the issue below.
+                        val resizeObserver = ResizeObserver { entries, _ ->
+                            val element = entries.first().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())
+                            */
+
+                            /* 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)
+                                }
+                            }
+                        }
+                        resizeObserver.observe(it)
+
+                        onDispose {
+                            //resizeObserver.unobserve(it)
+                            resizeObserver.disconnect()
+                            clientSize = null
+                        }
+                    }
                 }
             }
-        }.fillMaxSizeStretch()
             .then(modifier),
         contentAlignment
     ) {