anchor.diff:        }
       }
   
  -    if (hScrollDist != null || vScrollDist != null) {
  +    if ((hScrollDist != null && hScrollDist != 0) || (vScrollDist != null && vScrollDist != 0)) {
         if (_h_render != null) {
           _h_render.cancel();
         }
  
positive.code:       viewportTop = _scrollTop;
      }
      if (viewportLeft == null) {
        viewportLeft = scrollLeft;
      }
  
      return new Range(
  
negative.code:       ..style.position ='absolute'
        ..style.top ='0'
        ..style.left='0'
        ..style.width = '${_getCanvasWidth() + _scrollbarDimensions.x}px';
      _headerRowScroller.append(_headerRowSpacer);
  
      _topPanelScroller = new dom.DivElement()
  