Use case

When RawMenuAnchor closes on view size changes, we are currently triggering menu closure from didChangeDependencies using MediaQuery.sizeOf(context). Doing so triggers a build during SchedulerPhase.persistentCallbacks. While building during persistent callbacks normally throws an error, there are several areas in the RawMenuAnchor code where the SchedulerPhase is guarded to determine whether setState and OverlayController.show() should be called immediately or in a post-frame callback. This prevents errors, but also complicates the behavior of RawMenuAnchor.

I realized today that WidgetsBindingObserver.didChangeMetrics is called in the idle phase instead of during persistent callbacks, so switching from MediaQuery.sizeOf() to WidgetsBindingObserver.didChangeMetrics could avoid all of this phase checking. The downside is that the menu won't close if a user adds a MediaQuery widget above the menu.

Proposal

To fix the phase checks, we would just need to close RawMenuAnchor when didChangeMetrics is called:

  @override
  void didChangeMetrics() {
    super.didChangeMetrics();
    root.close();
  }