fix: NavigationBarDestination.selected_icon renders wrongly when set to a Control

.agents/skills/test-flet-apps-dev/SKILL.md

@@ -0,0 +1,152 @@
+---
+name: test-flet-apps-dev
+description: Use when testing or debugging Flet apps in maintainer/contributor development mode with local Python package sources and the local Flutter client, including web, desktop, browser, and computer-use verification workflows.
+---
+
+# Test Flet Apps In Dev Mode
+
+Use this skill when validating a Flet app, example, feature, or bug fix against
+this repo's local Python packages and/or local Flutter client during maintainer
+or contributor work.
+
+## Core model
+
+Flet dev-mode testing usually has one or two processes:
+
+1. A Python Flet app/server, run from `sdk/python`.
+2. The local Flutter client, run from `client`, when Dart/client or extension code
+   must be tested.
+
+If only Python code changed, `uv run flet run ...` is often enough. If Dart,
+Flutter, extension, or transport code changed, run the local Flutter client so
+the changed Dart code is actually used.
+
+The local Flutter client debug build uses a fixed app-server URL from
+`client/lib/main.dart`:
+
+```dart
+if (kDebugMode) {
+  pageUrl = "http://localhost:8550";
+}
+```
+
+Therefore, when using the local Flutter client without extra URL arguments,
+start the Python app on port `8550`.
+
+## Start the Python app
+
+Run from `{repo}/sdk/python`:
+
+```bash
+uv run flet run -w -p 8550 examples/controls/core/interactive_viewer/handling_events/main.py
+```
+
+Adjust the sample path as needed. Use port `8550` when the local Flutter client
+will connect with its default debug URL. Keep this process running and watch its
+stdout for Python callback output, tracebacks, and event payloads.
+
+For web-only checks with the packaged web client, open:
+
+```text
+http://127.0.0.1:8550
+```
+
+## Run the local Flutter client
+
+Run these from `{repo}/client`.
+
+### Desktop
+
+Use when validating native desktop behavior on the current host OS:
+
+```bash
+fvm flutter run -d macos     # macOS
+fvm flutter run -d windows   # Windows
+fvm flutter run -d linux     # Linux
+```
+
+The debug client defaults to `http://localhost:8550` when no app URL argument is
+provided. Use the platform target that exists on the current machine. Use
+Computer Use or the relevant platform automation to navigate and interact with
+the app window.
+
+### Flutter web in Chrome
+
+Use when Dart web behavior must be validated in Flutter's default web debug
+browser:
+
+```bash
+fvm flutter run -d chrome
+```
+
+This opens a fresh browser connected to the Python app server on port `8550`.
+
+### Flutter web in another Chromium browser
+
+If the requested browser is not listed by `flutter devices`, prefer the web
+server target and open the served URL in that browser:
+
+```bash
+fvm flutter run -d web-server --web-hostname 127.0.0.1 --web-port 8660
+open -a "Brave Browser" http://127.0.0.1:8660
+```
+
+Using `CHROME_EXECUTABLE` can work, but Flutter may fail to attach its debug
+websocket in non-default Chromium browsers. Fall back to `web-server` if that
+happens.
+
+## Browser and UI interaction
+
+- For local browser targets (`localhost`, `127.0.0.1`, `file://`), prefer the
+  in-app browser or the Browser Use plugin when explicitly requested.
+- Use Computer Use for native desktop apps and external browsers when browser
+  MCP is not the requested tool or cannot control that browser.
+- For chart/canvas-heavy UI, click/hover coordinates may be necessary because
+  accessibility trees often expose only the HTML canvas container.
+
+## Reading evidence
+
+Always inspect both sides:
+
+- Python app stdout: event payloads, user `print()` calls, Python tracebacks.
+- Flutter run stdout: client-side event payloads, WebSocket messages, Flutter
+  exceptions, hot reload/restart status.
+- Browser/app state: the actual rendered UI and any visible error banner.
+
+For client/server protocol bugs, compare the raw outgoing Dart event in Flutter
+logs with the decoded Python event object in Python logs.
+
+## Hot reload and restart
+
+For Flutter client sessions:
+
+- Press `r` for hot reload after many Dart-only edits.
+- Press `R` for hot restart if state, initialization, or extension registration
+  may be stale.
+- Quit with `q` before final response unless the user explicitly wants the app
+  left running.
+- Press `h` for help on other Flutter run key commands.
+
+For Python app sessions, restart `uv run flet run ...` after Python source or
+sample changes if the running process does not pick them up.
+
+## Troubleshooting
+
+- If a sandboxed Flutter command fails trying to write FVM or Flutter cache files
+  such as `engine.stamp`, rerun the same command with escalation.
+- If `flutter devices` does not list Brave/Edge/etc., use `flutter run -d web-server`
+  and open the URL in the target browser.
+- If the UI shows a generic Flet error banner, check Python stdout first; the
+  root cause is often a handler exception.
+- If an event handler indexes a list payload, confirm the empty-list case before
+  treating it as a framework bug.
+- If the local Flutter client cannot connect, confirm the Python app is running
+  on port `8550` or pass an explicit app URL when the client path supports it.
+
+## Finish checklist
+
+- Stop long-running app/test sessions unless asked to leave them running.
+- State exactly which surfaces were tested: packaged web, local Flutter web,
+  desktop target, target browser, or sample-only.
+- Include the key observed payload/error before and after the fix.
+- Separate framework bugs from sample-code guard issues.

CHANGELOG.md

@@ -32,7 +32,9 @@
 * Fix `Page.on_resize` and `Page.on_media_change` not firing after mobile orientation changes ([#6457](https://github.com/flet-dev/flet/issues/6457), [#6423](https://github.com/flet-dev/flet/pull/6423)) by @ndonkoHenri.
 * Fix `flet pack` desktop packaging so Windows and Linux bundles include the expected client archive, and Windows taskbar pins point to the packed app instead of the cached `flet.exe` ([#5151](https://github.com/flet-dev/flet/issues/5151), [#6403](https://github.com/flet-dev/flet/pull/6403)) by @ndonkoHenri.
 * Fix environment variable priority in `flet build` template: inherit from `Platform.environment` and use `putIfAbsent` for FLET_* variables so pre-set system env vars are not overwritten ([#6394](https://github.com/flet-dev/flet/pull/6394)) by @Bahtya.
+* Fix `NavigationBarDestination.selected_icon` rendering wrongly when provided as an `Icon` control ([#6460](https://github.com/flet-dev/flet/issues/6460), [#6468](https://github.com/flet-dev/flet/pull/6468)) by @ndonkoHenri.
 * Fix 3- and 4-digit hex color shorthand (e.g. `#c00`, `#fc00`) rendering as invisible by expanding them to their full 6/8-digit forms ([#6419](https://github.com/flet-dev/flet/issues/6419), [#6421](https://github.com/flet-dev/flet/pull/6421)) by @ndonkoHenri.
+* Fix `LineChartEvent.spots` returning undecoded MessagePack extension values instead of `LineChartEventSpot` objects ([#6443](https://github.com/flet-dev/flet/issues/6443), [#6468](https://github.com/flet-dev/flet/pull/6468)) by @ndonkoHenri.
 * Fix `LineChart` (and other charts) silently dropping custom `ChartAxisLabel` entries whose `value` matched a tick only after floating-point rounding (e.g. `0.1`, `0.2`, `0.3`) by switching label lookup to a tolerance-based comparison scaled to the axis interval ([#6445](https://github.com/flet-dev/flet/issues/6445), [#6459](https://github.com/flet-dev/flet/pull/6459)) by @KangZhaoKui.
 * Fix absolute-path `src` (e.g. `Image(src="/images/foo.svg")`) breaking on web when the app is mounted at a non-root URL, pass `data:`/`blob:` URIs through the asset resolver unchanged, preserve origin-relative semantics when `assets_dir` is unset, and add a `window.flet.assetsDir` JS-interop bridge so embedding hosts can supply `assets_dir` to the top-level `FletApp` ([#6470](https://github.com/flet-dev/flet/pull/6470)) by @FeodorFitsner.
 

packages/flet/lib/src/controls/navigation_bar_destination.dart

@@ -2,7 +2,6 @@ import 'package:flutter/material.dart';
 
 import '../extensions/control.dart';
 import '../models/control.dart';
-import '../utils/icons.dart';
 import '../utils/numbers.dart';
 import 'base_controls.dart';
 
@@ -15,14 +14,13 @@ class NavigationBarDestinationControl extends StatelessWidget {
   Widget build(BuildContext context) {
     debugPrint("NavigationBarDestination build: ${control.id}");
 
-    var selectedIcon = control.getIconData("selected_icon");
     var child = NavigationDestination(
-        enabled: !control.disabled,
-        tooltip: !control.disabled ? control.getString("tooltip") : null,
-        icon: control.buildIconOrWidget("icon")!,
-        selectedIcon: control.buildWidget("selected_icon") ??
-            (selectedIcon != null ? Icon(selectedIcon) : null),
-        label: control.getString("label", "")!);
+      enabled: !control.disabled,
+      tooltip: !control.disabled ? control.getString("tooltip") : null,
+      icon: control.buildIconOrWidget("icon")!,
+      selectedIcon: control.buildIconOrWidget("selected_icon"),
+      label: control.getString("label", "")!,
+    );
 
     return BaseControl(control: control, child: child);
   }

packages/flet/lib/src/controls/scrollable_control.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
 
 import '../models/control.dart';
 import '../utils/animations.dart';
@@ -32,6 +33,7 @@ class _ScrollableControlState extends State<ScrollableControl>
     with FletStoreMixin {
   late final ScrollController _controller;
   late bool _ownController = false;
+  final _ConstraintsHolder _outerConstraints = _ConstraintsHolder();
 
   @override
   void initState() {
@@ -111,34 +113,29 @@ class _ScrollableControlState extends State<ScrollableControl>
 
     Widget child = widget.child;
     if (widget.wrapIntoScrollableView) {
-      child = LayoutBuilder(builder: (context, constraints) {
-        final minWidth = widget.scrollDirection == Axis.horizontal &&
-                constraints.hasBoundedWidth
-            ? constraints.maxWidth
-            : 0.0;
-        final minHeight = widget.scrollDirection == Axis.vertical &&
-                constraints.hasBoundedHeight
-            ? constraints.maxHeight
-            : 0.0;
-
-        Widget scrollViewChild = widget.child;
-        if (minWidth > 0 || minHeight > 0) {
-          scrollViewChild = ConstrainedBox(
-            constraints:
-                BoxConstraints(minWidth: minWidth, minHeight: minHeight),
-            child: scrollViewChild,
-          );
-        }
-
-        return SingleChildScrollView(
-          controller: _controller,
+      // The pre-#6450 path used a plain SingleChildScrollView. PR #6450 added
+      // a LayoutBuilder + ConstrainedBox(minHeight: parentMaxHeight) wrapper
+      // so vertical alignment works in scrollable Page/View when content is
+      // shorter than the viewport. LayoutBuilder, however, reports 0 for
+      // intrinsic dimensions, which collapses any ancestor IntrinsicWidth /
+      // IntrinsicHeight and leaves the layout perpetually dirty.
+      //
+      // Replicate the behavior with two cooperating RenderProxyBoxes that
+      // forward intrinsic queries to their child. The outer reader captures
+      // the parent's constraints during performLayout; the inner enforcer
+      // reads them back and applies them as a min on the scroll-view child.
+      child = SingleChildScrollView(
+        controller: _controller,
+        scrollDirection: widget.scrollDirection,
+        child: _InnerConstraintsEnforcer(
+          holder: _outerConstraints,
           scrollDirection: widget.scrollDirection,
-          child: scrollViewChild,
-        );
-      });
+          child: widget.child,
+        ),
+      );
     }
 
-    return Scrollbar(
+    Widget result = Scrollbar(
         thumbVisibility: scrollConfiguration.thumbVisibility,
         trackVisibility: scrollConfiguration.trackVisibility,
         thickness: scrollConfiguration.thickness,
@@ -150,5 +147,122 @@ class _ScrollableControlState extends State<ScrollableControl>
           behavior: ScrollConfiguration.of(context).copyWith(scrollbars: false),
           child: child,
         ));
+
+    if (widget.wrapIntoScrollableView) {
+      result = _OuterConstraintsReader(
+        holder: _outerConstraints,
+        child: result,
+      );
+    }
+
+    return result;
+  }
+}
+
+/// Carries box constraints from [_OuterConstraintsReader] (outside the scroll
+/// view) to [_InnerConstraintsEnforcer] (inside it) within a single layout
+/// pass. Holds a reference to the inner enforcer so the outer reader can
+/// mark it dirty when its incoming constraints change — without that, the
+/// inner enforcer would skip re-layout on window resize because the
+/// constraints it sees from SingleChildScrollView (unbounded in scroll axis)
+/// don't change.
+class _ConstraintsHolder {
+  BoxConstraints? value;
+  RenderObject? listener;
+}
+
+class _OuterConstraintsReader extends SingleChildRenderObjectWidget {
+  const _OuterConstraintsReader({required this.holder, super.child});
+  final _ConstraintsHolder holder;
+
+  @override
+  RenderObject createRenderObject(BuildContext context) =>
+      _RenderOuterConstraintsReader(holder);
+
+  @override
+  void updateRenderObject(
+      BuildContext context, _RenderOuterConstraintsReader renderObject) {
+    renderObject.holder = holder;
+  }
+}
+
+class _RenderOuterConstraintsReader extends RenderProxyBox {
+  _RenderOuterConstraintsReader(this.holder);
+  _ConstraintsHolder holder;
+
+  @override
+  void performLayout() {
+    final changed = holder.value != constraints;
+    holder.value = constraints;
+    if (changed && holder.listener != null) {
+      // Force the inner enforcer to re-run performLayout in this layout pass.
+      // invokeLayoutCallback enables mutations during layout — without it,
+      // markNeedsLayout asserts.
+      invokeLayoutCallback<BoxConstraints>((_) {
+        holder.listener?.markNeedsLayout();
+      });
+    }
+    super.performLayout();
+  }
+}
+
+class _InnerConstraintsEnforcer extends SingleChildRenderObjectWidget {
+  const _InnerConstraintsEnforcer({
+    required this.holder,
+    required this.scrollDirection,
+    super.child,
+  });
+  final _ConstraintsHolder holder;
+  final Axis scrollDirection;
+
+  @override
+  RenderObject createRenderObject(BuildContext context) =>
+      _RenderInnerConstraintsEnforcer(holder, scrollDirection);
+
+  @override
+  void updateRenderObject(
+      BuildContext context, _RenderInnerConstraintsEnforcer renderObject) {
+    renderObject
+      ..holder = holder
+      ..scrollDirection = scrollDirection;
+  }
+}
+
+class _RenderInnerConstraintsEnforcer extends RenderProxyBox {
+  _RenderInnerConstraintsEnforcer(this.holder, this.scrollDirection);
+  _ConstraintsHolder holder;
+  Axis scrollDirection;
+
+  @override
+  void attach(PipelineOwner owner) {
+    super.attach(owner);
+    holder.listener = this;
+  }
+
+  @override
+  void detach() {
+    if (holder.listener == this) holder.listener = null;
+    super.detach();
+  }
+
+  @override
+  void performLayout() {
+    if (child == null) {
+      size = computeSizeForNoChild(constraints);
+      return;
+    }
+    BoxConstraints childConstraints = constraints;
+    final outer = holder.value;
+    if (outer != null) {
+      if (scrollDirection == Axis.vertical && outer.hasBoundedHeight) {
+        childConstraints =
+            childConstraints.copyWith(minHeight: outer.maxHeight);
+      } else if (scrollDirection == Axis.horizontal && outer.hasBoundedWidth) {
+        childConstraints =
+            childConstraints.copyWith(minWidth: outer.maxWidth);
+      }
+    }
+    child!.layout(childConstraints, parentUsesSize: true);
+    size = child!.size;
   }
 }

sdk/python/examples/extensions/map/basic/main.py

@@ -10,9 +10,11 @@ def main(page: ft.Page):
                 expand=True,
                 layers=[
                     ftm.TileLayer(
-                        url_template="https://tile.memomaps.de/tilegen/{z}/{x}/{y}.png",
+                        url_template="https://tile.openstreetmap.org/{z}/{x}/{y}.png",
+                        user_agent_package_name="flet-map-examples/1.0",
                         on_image_error=lambda e: print(f"TileLayer Error: {e.data}"),
                     ),
+                    ftm.SimpleAttribution(text="OpenStreetMap contributors"),
                 ],
             ),
         )