anchor.diff:    /// [render] method. When possible, this is driven by the hardware VSync
     /// signal. This is only called if [scheduleFrame] has been called since the
     /// last time this callback was invoked.
  +  ///
  +  /// The [onDrawFrame] callback is invoked immediately after [onBeginFrame],
  +  /// after draining any microtasks (e.g. completions of any [Future]s) queued
  +  /// by the [onBeginFrame] handler.
     FrameCallback onBeginFrame;
   
  -  /// A callback that is invoked for each frame after onBeginFrame has
  -  /// completed and after the microtask queue has been drained.  This can be
  +  /// A callback that is invoked for each frame after [onBeginFrame] has
  +  /// completed and after the microtask queue has been drained. This can be
     /// used to implement a second phase of frame rendering that happens
  -  /// after any deferred work queued by the onBeginFrame phase.
  +  /// after any deferred work queued by the [onBeginFrame] phase.
     VoidCallback onDrawFrame;
   
     /// A callback that is invoked when pointer data is available.
  
positive.code:   String _defaultRouteName;
  
    /// Requests that, at the next appropriate opportunity, the [onBeginFrame]
    /// callback be invoked.
    void scheduleFrame() native "Window_scheduleFrame";
  
    /// Updates the application's rendering on the GPU with the newly provided
    /// [Scene]. This function must be called within the scope of the
    /// [onBeginFrame] callback being invoked. If this function is called multiple
    /// times during a single [onBeginFrame] callback or called outside the scope
    /// of an [onBeginFrame], the call will be ignored.
    ///
    /// To record graphical operations, first create a [PictureRecorder], then
    /// construct a [Canvas], passing that [PictureRecorder] to its constructor.
  
negative.code: enum AppLifecycleState {
    /// The application is not currently visible to the user. When the
    /// application is in this state, the engine will not call the
    /// [Window.onBeginFrame] and [Window.onDrawFrame] callbacks.
    paused,
  
    /// The application is visible to the user.
  