anchor.diff:  
     /// Requests that, at the next appropriate opportunity, the [onBeginFrame]
     /// and [onDrawFrame] callbacks be invoked.
  +  ///
  +  /// See also:
  +  ///
  +  ///  * [SchedulerBinding], the Flutter framework class which manages the
  +  ///    scheduling of frames.
     void scheduleFrame() native "Window_scheduleFrame";
   
     /// Updates the application's rendering on the GPU with the newly provided
  
positive.code:   /// should, if possible, use to render their user interface.
    ///
    /// The [onLocaleChanged] callback is called whenever this value changes.
    Locale get locale => _locale;
    Locale _locale;
  
    /// A callback that is invoked whenever [locale] changes value.
    VoidCallback onLocaleChanged;
  
    /// A callback that is invoked to notify the application that it is an
  
negative.code:   /// hardware itself, the device drivers, or a hard-coded value stored in the
    /// operating system or firmware, and may be inaccurate, sometimes by a
    /// significant margin.
    ///
    /// The Flutter framework operates in logical pixels, so it is rarely
    /// necessary to directly deal with this property.
    ///
    /// See also:
    ///
    ///  * [WidgetsBindingObserver], for a mechanism at the widgets layer to
    ///    observe when this value changes.
    double get devicePixelRatio => _devicePixelRatio;
    double _devicePixelRatio = 1.0;
  
    /// The dimensions of the rectangle into which the application will be drawn,
    /// in physical pixels.
    ///
    /// See also:
    ///
    ///  * [WidgetsBindingObserver], for a mechanism at the widgets layer to
    ///    observe when this value changes.
    Size get physicalSize => _physicalSize;
    Size _physicalSize = Size.zero;
  
  