anchor.diff:          ..attributes.remove('id')
           ..style.cursor = 'inherit';
       
  -    // Set the initial position of avatar.
  -    setLeftTop(draggable.documentOffset);
  -    
       // Ensure avatar has an absolute position.
       avatar.style.position = 'absolute';
       avatar.style.zIndex = '100';
  +    
  +    // Set the initial position of avatar.
  +    setLeftTop(draggable.documentOffset);
       
       // Set pointer-events to none.
       setPointerEventsNone();
  
positive.code:   /// Returns the (cached) left margin of [avatar].
    num get marginLeft {
      if (_marginLeft == null) {
        _cacheMargins();
      }
      return _marginLeft;
    }
  
negative.code:   /// Returns the (cached) top margin of [avatar].
    num get marginTop {
      if (_marginTop == null) {
        cacheMargins();
      }
      return _marginTop;
    }
  