anchor.diff:        _draggable.style
             ..left = "0"
             ..right = "0"
  -          ..top = "-3px"
  -          ..height = "7px";
  +          ..top = "-${draggableStart}px"
  +          ..height = "${draggableSize}px";
       } else {
         style
             ..height = "auto"
  
positive.code:   }
  
    void _setThickness() {
      final sizeStr = '${size}px';
      if (_isHorizontal) {
        style
            ..height = sizeStr
  
negative.code:       _draggable.style
            ..bottom = "0"
            ..top = "0"
            ..left = "-${draggableStart}px"
            ..width = "${draggableSize}px";
      }
    }
  
  