static JMenu addMenu(JComponent c, S menuName, O... items) {
  ret addMenu(getFrame(c), menuName, items);
}

static JMenu addMenu(JFrame frame, S menuName, O... items) {
  JMenuBar bar = addMenuBar(frame);
  JMenu menu = getMenuNamed(bar, menuName);
  bool isNew = menu == null;
  if (isNew)
    menu = new JMenu(menuName);
  else
    menu.removeAll();
  fillJMenu(menu, items);
  if (isNew) {
    bar.add(menu);
    revalidateFrame(frame);
  }
  ret menu;
}