@Override
    public void drop(DnDEvent aEvent) {
      setDropTargetIndex(-1);
      if (aEvent.getAttachedObject() instanceof PaletteItem) {
        int index = locationToTargetIndex(aEvent.getPoint());
        if (index >= 0) {
          myGroup.handleDrop(myProject, (PaletteItem) aEvent.getAttachedObject(), index);
        }
      }
    }
@Override
    public void drop(DnDEvent aEvent)