anchor.diff:                     ..height = height.toString();
       _nodeLabel = new NodeLabel(this);
       _tooltip = new Tooltip(this);
  +    _rectifyAppearance();
       _dataModel.onPropertyChange.listen((_) { 
         if (viewModel.treemap.automaticUpdates) { 
           repaintContent(); 
         } 
  -    });
  -    parent.then((_) {
  -      _rectifyAppearance();
       });
     }
     
  
positive.code:     return rootNode;
    }
    
    DataModel get dataModel;
  
    void repaintContent();
  
    bool get isLeaf => dataModel.isLeaf;
  
    bool get isBranch => dataModel.isBranch;
  
negative.code: 
    int get clientHeight => _content.clientHeight;
    
    DataModel get dataModel;
  
    void repaintContent();
  
  }