anchor.diff:          onTap: _pushScreenToLocalPageRoute,
           tabs: [for (var screen in widget.tabs) screen.buildTab(context)],
         );
  -      preferredSize = Tween<Size>(
  -        begin: const Size.fromHeight(kToolbarHeight),
  -        end: const Size.fromHeight(kToolbarHeight + 40.0),
  -      ).evaluate(appBarCurve);
  -      final animatedAlignment = Tween<Alignment>(
  -        begin: Alignment.centerRight,
  -        end: Alignment.bottomLeft,
  -      ).evaluate(appBarCurve);
  +      preferredSize = isNarrow
  +          ? const Size.fromHeight(kToolbarHeight + 40.0)
  +          : const Size.fromHeight(kToolbarHeight);
  +      final alignment = isNarrow ? Alignment.bottomLeft : Alignment.centerRight;
   
         final rightAdjust =
             isNarrow ? 0.0 : DevToolsScaffold.actionWidgetSize / 2;
  -      final animatedRightPadding = Tween<double>(
  -        begin: math.max(
  -            0.0,
  -            DevToolsScaffold.actionWidgetSize * (actions?.length ?? 0.0) -
  -                rightAdjust),
  -        end: 0.0,
  -      ).evaluate(appBarCurve);
  +      final rightPadding = isNarrow
  +          ? 0.0
  +          : math.max(
  +              0.0,
  +              DevToolsScaffold.actionWidgetSize * (actions?.length ?? 0.0) -
  +                  rightAdjust);
   
         flexibleSpace = Align(
  -        alignment: animatedAlignment,
  +        alignment: alignment,
           child: Padding(
             padding: EdgeInsets.only(
               top: 4.0,
  -            right: animatedRightPadding,
  +            right: rightPadding,
             ),
             child: tabBar,
           ),
  
positive.code:       Notifications.of(context),
        _pushSnapshotScreenForImport,
      );
  
      // If the animations are null, initialize them.
      appBarAnimation ??= defaultAnimationController(
        this,
        value: isNarrow ? 1.0 : 0.0,
      );
      appBarCurve ??= defaultCurvedAnimation(appBarAnimation);
      if (isNarrow) {
        appBarAnimation.forward();
      } else {
        appBarAnimation.reverse();
      }
    }
  
    @override
    void dispose() {
      _tabController?.dispose();
      _currentScreen?.dispose();
      appBarAnimation?.dispose();
      _connectVmSubscription?.cancel();
      _showPageSubscription?.cancel();
  
  
negative.code:           // TODO(kenz): we are handling drops from multiple scaffolds. We need
            // to make sure we are only handling drops from the active scaffold.
            handleDrop: _importController.importData,
            child: Scaffold(
              appBar: _buildAppBar(),
              body: TabBarView(
                physics: defaultTabBarViewPhysics,
                controller: _tabController,
                children: tabBodies,
              ),
              bottomNavigationBar: _buildStatusLine(context),
            ),
          ),
        ),
  