private void addMenuItem(final ActionID id, final Class<?> lookup, final JMenu menu,
      final ButtonGroup group) {
    final JRadioButtonMenuItem item = id == null ? new JRadioButtonMenuItem()
    : new JRadioButtonMenuItem(ctrl.getActionFor(id));
    if(group != null) {
      group.add(item);
    }
    if(menu != null) {
      menu.add(item);
    } else {
      item.setVisible(false);
    }
    ctrl.registerDisplayMenuItem(lookup, item);
  }