DnDConstants.ACTION_LINK, //specifies valid actions
this //DragGestureListener
);
dgr.setSourceActions(dgr.getSourceActions() & ~InputEvent.BUTTON3_MASK);
DropTarget dropTarget = new DropTarget(this, this);
final JPopupMenu popupMenu = new JPopupMenu();
JMenuItem menuItem = new JMenuItem("Unlink");
menuItem.addActionListener(new ActionListener(){