anchor.diff:  
       _dragOverlay = new DivElement();
       _dragOverlay.classes.add('treeviewcell-dragoverlay');
  -    _dragOverlay.style.left = (margin + 15).toString() + 'px';
  +    _dragOverlay.style.left = '${margin + 15}px';
       offsetX = margin + 20;
       _dragOverlay.style.width = 'calc(100% - ${offsetX}px)';
       _element.children.add(_dragOverlay);
  
positive.code:       // Adds an arrow in front the cell.
        _arrow = new DivElement();
        _arrow.classes.add('treeviewcell-disclosure');
        _arrow.style.left = margin.toString() + 'px';
        _arrow.appendHtml('&#9654;');
        _applyExpanded(_row.expanded);
        _element.children.add(_arrow);
  
negative.code:     _embeddedCellContainer = new DivElement();
      int margin = (_row.level * 10);
      _embeddedCellContainer.classes.add('treeviewcell-content');
      _embeddedCellContainer.style.left = '${margin + 20}px';
      int offsetX = margin + 30;
      _embeddedCellContainer.style.width = 'calc(100% - ${offsetX}px)';
      _embeddedCellContainer.children.add(_embeddedCell.element);
  