static JMenuBar addMenuBar(RootPaneContainer f) {
  if (f == null) null;
  JMenuBar bar = cast call(f, 'getJMenuBar);
  if (bar == null) {
    setMenuBar(f, bar = new JMenuBar());
    revalidate((Component) f);
  }
  ret bar;
}

static JMenuBar addMenuBar(Component c) {
  ret addMenuBar(getPossiblyInternalFrame(c));
}

static JMenuBar addMenuBar(JFrame f) {
  ret addMenuBar((RootPaneContainer) f);
}