anchor.diff:    Tab _selectedTab;
     bool _tabItemsLayoutListenerEnabled = false;
     int _lastLayoutWidth = 0;
  -  StreamSubscription<MouseEvent> _tabViewContainerMouseOutStream;
  -  StreamSubscription<MouseEvent> _documentMouseOutStream;
  +  StreamSubscription<MouseEvent> _tabBarMouseLeaveStream;
   
     TabView(this.parentElement) {
       List<Element> originalElements = parentElement.children.toList();
  
positive.code:     });
  
      if (_tabItemsLayoutListenerEnabled) {
        _tabViewContainerMouseOutStream.cancel();
        _tabViewContainerMouseOutStream = null;
        _documentMouseOutStream.cancel();
        _documentMouseOutStream = null;
        _tabItemsLayoutListenerEnabled = false;
      }
    }
  
negative.code:       return;
      }
      _tabItemsLayoutListenerEnabled = true;
      _tabBarMouseLeaveStream = _tabBar.onMouseLeave.listen((e) {
        _layoutTabItems();
      });
    }
  