sclass componentPopupMenu_Maker {
  new L menuMakers;
}

static Map<JComponent, componentPopupMenu_Maker> componentPopupMenu_map = new WeakHashMap;

static new ThreadLocal<MouseEvent> componentPopupMenu_mouseEvent;

// menuMaker = voidfunc(JPopupMenu)
static void componentPopupMenu(final JComponent component, fO menuMaker) {
  awtIfNecessary {
    componentPopupMenu_Maker maker = componentPopupMenu_map.get(component);
    if (maker == null) {
      componentPopupMenu_map.put(component, maker = new componentPopupMenu_Maker);
      component.addMouseListener(new componentPopupMenu_Adapter(maker));
    }
    maker.menuMakers.add(menuMaker);
  }
}

sclass componentPopupMenu_Adapter extends MouseAdapter {
  componentPopupMenu_Maker maker;
  
  *(componentPopupMenu_Maker maker) {}
  
  public void mousePressed(MouseEvent e) { displayMenu(e); }
  public void mouseReleased(MouseEvent e) { displayMenu(e); }

  void displayMenu(MouseEvent e) {
    if (!e.isPopupTrigger()) ret;
    new JPopupMenu menu;
    int emptyCount = menu.getComponentCount();
    
    componentPopupMenu_mouseEvent.set(e);
    for (O menuMaker : maker.menuMakers)
      pcallF(menuMaker, menu);
    
    // show menu if any items in it
    if (menu.getComponentCount() != emptyCount)
      menu.show(e.getComponent(), e.getX(), e.getY());
  }
}