svoid makePopupMenuFullyDynamic(JMenu menu, final VF1<JPopupMenu> populate) {
  addMenuListener(menu, new PopupMenuListener {
    public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
      clearPopupMenu(menu);
      callF(populate, menu);
    }
    
    public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
      clearPopupMenu(menu);
    }
    
    public void popupMenuCanceled(PopupMenuEvent e) {
      clearPopupMenu(menu);
    }
  });
}

Began life as a copy of #1020521