static void listDependButtons(JList tbl, L<? extends Component> buttons) {
  for (Component c : buttons)
    if (c instanceof JButton) {
      final JButton b = cast c;
      list.addListSelectionListener(new ListSelectionListener {
        public void valueChanged(ListSelectionEvent e) {
          b.setEnabled(list.getSelectedIndex() >= 0);
        }
      });
      b.setEnabled(list.getSelectedIndex() >= 0);
    }
}