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);
      final componentPopupMenu_Maker _maker = maker;
      component.addMouseListener(new MouseAdapter {
        public void mousePressed(MouseEvent e) { displayMenu(e); }
        public void mouseReleased(MouseEvent e) { displayMenu(e); }
      
        void displayMenu(MouseEvent e) {
          if (e.isPopupTrigger()) {
            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());
          }
        }
      });
    }
    maker.menuMakers.add(menuMaker);
  }
}

Began life as a copy of #1005719