anchor.diff:    
     DataModel get model => this._model;
     
  +  ViewNode get parent => this._parent;
  +  
   }
  
positive.code:         ..margin = "0px"
          ..padding = "0px"
          ..position = "absolute"
          ..left = "${padding}px"
          ..right = "${padding}px"
          ..bottom = "${padding}px"
          ..top = "${labelHeight + padding}px";
      _container.children.add(_nodeLabel);
      _container.children.add(_content);
    }
    
    void _fixBorders(ViewNode node) {
      int index = this._children.lastIndexOf(node) - 1;
      if (index > -1) {
        ViewNode previousSibling = this._children[index];
        if (!previousSibling.isRoot()) {
          if (previousSibling._orientation == HORIZONTAL_ORIENTATION) {
            node._container.style.borderLeftWidth = "0px";
          } else {
            node._container.style.borderTopWidth = "0px";
          }
        }
      }
    }
  
    void add(ViewNode child) {
      _content.children.add(child._container);
      this._children.add(child);
      _fixBorders(child);
    }
  
negative.code:   static const String VERTICAL_ORIENTATION = "none";
    static const String HORIZONTAL_ORIENTATION = "left";
    final List<ViewNode> _children = new List();
    ViewNode _parent;
    String _orientation = VERTICAL_ORIENTATION;
    DataModel _model;
    DivElement _container;
    DivElement _content;
    ParagraphElement _nodeLabel;
    final int _labelHeight = 19;
    final int _padding = 3;
  
    ViewNode(this._model, num width, num height, [this._orientation]) {
      assert(this._model != null);
  