anchor.diff:      int vScrollDist = (_scrollTop - _prevScrollTop).abs();
       int hScrollDist = (_scrollLeft - _prevScrollLeft).abs();
   
  -    if (hScrollDist != null && hScrollDist != 0) {
  +    if (hScrollDist != 0) {
         _prevScrollLeft = _scrollLeft;
         _headerScroller.scrollLeft = _scrollLeft;
         _topPanelScroller.scrollLeft = _scrollLeft;
         _headerRowScroller.scrollLeft = _scrollLeft;
       }
   
  -    if (vScrollDist != null && vScrollDist != 0) {
  +    if (vScrollDist != 0) {
         _vScrollDir = _prevScrollTop < _scrollTop ? 1 : -1;
         _prevScrollTop = _scrollTop;
   
  
positive.code:       }
      }
  
      if ((hScrollDist != null && hScrollDist != 0) || (vScrollDist != null && vScrollDist != 0)) {
        if (_h_render != null) {
          _h_render.cancel();
        }
  
negative.code:       }
      }
  
      if (rowElement.children.length == 0) {
        return;
      }
  
  