sclass PopupMenuMaker {
  settable bool allowScrolling = true; // ignored when using existingMenu
  settable MouseEvent event;
  settable IVF1<JPopupMenu> fillMenu;
  settable JPopupMenu existingMenu;
  settable bool addSeparator = true; // add separator if existing meun
  
  JPopupMenu menu;
  
  *() {}
  *(MouseEvent *event, IVF1<JPopupMenu> *fillMenu) {}

  public void run() swing {
    if (existingMenu != null) {
      int emptyCount = existingMenu.getComponentCount();
      if (addSeparator)
        existingMenu.addSeparator();
      int emptyCount2 = existingMenu.getComponentCount();
      fillMenu?.get(existingMenu);
      if (menu.getComponentCount() == emptyCount2)
        truncateContainer(menu, emptyCount);
      printVars("Extended popup menu", +emptyCount, +emptyCount2, n := menu.getComponentCount());
      // TODO: revalidate popup?
    } else {
      new JPopupMenu menu;
      
      int emptyCount = menu.getComponentCount();
      fillMenu?.get(menu);
      if (menu.getComponentCount() == emptyCount)
        ret;
    
      if (allowScrolling && existingMenu == null) {
        menu = new JPopupMenu;
        JMenuScroller scroller = JMenuScroller.setScrollerFor(menu);
        scroller.fillMenu = toVF1(fillMenu);
      }
    
      menu.show(event.getComponent(), event.getX(), event.getY());
    }
  }
}