anchor.diff:    }
   
     void _setThickness() {
  -    final sizeStr = '${size}px';
  +    final String sizeStr = '${size}px';
  +    final int draggableSize = math.max(size, _MIN_DRAGGABLE_SIZE);
  +    final int draggableStart = ((draggableSize - size) / 2).ceil();
  +    
       if (_isHorizontal) {
         style
             ..height = sizeStr
  
positive.code: 
  @CustomTag('spark-splitter')
  class SparkSplitter extends SparkWidget {
    /// Possible values are "left", "right", "up" and "down".
    /// The direction specifies:
    /// 1) whether the split is horizontal or vertical;
  
negative.code:       _draggable.style
            ..bottom = "0"
            ..top = "0"
            ..left = "-${draggableStart}px"
            ..width = "${draggableSize}px";
      }
    }
  
  