scope componentPopupMenu.

static ThreadLocal<MouseEvent> #mouseEvent;

svoid componentPopupMenu_init {
  swing {
    if (mouseEvent == null)
      mouseEvent = (ThreadLocal<MouseEvent>) vm_generalMap_get('mouseEvent);
    if (mouseEvent == null)
      vm_generalMap_put(componentPopupMenu_mouseEvent := mouseEvent = new ThreadLocal);
  }
}

// menuMaker = voidfunc(JPopupMenu)
static void componentPopupMenu(final JComponent component, fO menuMaker) {
  componentPopupMenu_init();
  if (component != null && menuMaker != null) swing {
    O adapter = findComponentPopupMenuListener_gen(component);
    if (adapter == null)
      component.addMouseListener(adapter = new componentPopupMenu_Adapter);
    }
    ((L) get(adapter, 'maker)).add(menuMaker);
  }
}

sclass componentPopupMenu_Adapter extends MouseAdapter {
  new L maker; // list of "menu makers" that fill the menu (IVF1<JPopupMenu>)
  
  public void mousePressed(MouseEvent e) { displayMenu(e); }
  public void mouseReleased(MouseEvent e) { displayMenu(e); }

  void displayMenu(MouseEvent e) {
    if (e.getSource() instanceof JInternalFrame) ret;
    if (e.isPopupTrigger()) displayMenu2(e);
  }
    
  void displayMenu2(MouseEvent e) {
    new JPopupMenu menu;
    int emptyCount = menu.getComponentCount();
    
    temp tempSetTL(mouseEvent, e);
    for (O menuMaker : maker)
      pcallF(menuMaker, menu);
      
    vmBus_send('showingPopupMenu, e.getComponent(), menu);
    
    // show menu if any items in it
    if (menu.getComponentCount() != emptyCount)
      menu.show(e.getComponent(), e.getX(), e.getY());
  }
}

end scope

Began life as a copy of #1005719