anchor.diff:    }
   
     @override
  +  void didChangeDependencies() {
  +    final MediaQueryData mediaQuery = MediaQuery.of(context);
  +    // If we transition from accessible navigation to non-accessible navigation
  +    // and there is a SnackBar that would have timed out that has already
  +    // completed its timer, dismiss that SnackBar. If the timer hasn't finished
  +    // yet, let it timeout as normal.
  +    if (_accessibleNavigation == true
  +      && !mediaQuery.accessibleNavigation
  +      && _snackBarTimer != null
  +      && !_snackBarTimer.isActive) {
  +      hideCurrentSnackBar(reason: SnackBarClosedReason.timeout);
  +    }
  +    _accessibleNavigation = mediaQuery.accessibleNavigation;
  +    super.didChangeDependencies();
  +  }
  +
  +  @override
     void dispose() {
       _snackBarController?.dispose();
       _snackBarTimer?.cancel();
  
positive.code:     final MediaQueryData mediaQuery = MediaQuery.of(context);
      final ThemeData themeData = Theme.of(context);
      final TextDirection textDirection = Directionality.of(context);
  
      if (_snackBars.isNotEmpty) {
        final ModalRoute<dynamic> route = ModalRoute.of(context);
        if (route == null || route.isCurrent) {
          if (_snackBarController.isCompleted && _snackBarTimer == null) {
            final SnackBar snackBar = _snackBars.first._widget;
            _snackBarTimer = new Timer.periodic(snackBar.duration, (Timer timer) {
              assert(_snackBarController.status == AnimationStatus.forward ||
                     _snackBarController.status == AnimationStatus.completed);
              // Look up MediaQuery again in case the setting changed.
              final MediaQueryData mediaQuery = MediaQuery.of(context);
              if (mediaQuery.accessibleNavigation && snackBar.action != null)
                return;
              timer.cancel();
              hideCurrentSnackBar(reason: SnackBarClosedReason.timeout);
            });
          }
  
negative.code:   final Queue<ScaffoldFeatureController<SnackBar, SnackBarClosedReason>> _snackBars = new Queue<ScaffoldFeatureController<SnackBar, SnackBarClosedReason>>();
    AnimationController _snackBarController;
    Timer _snackBarTimer;
    bool _accessibleNavigation;
  
    /// Shows a [SnackBar] at the bottom of the scaffold.
    ///
  