static void textComponentDependButtons(final JTextComponent tc, L<? extends Component> buttons) {
  for (Component c : buttons)
    if (c instanceof JButton) {
      final JButton b = cast c;
      tc.addCaretListener(new CaretListener {
        public void caretUpdate(CaretEvent e) {
          b.setEnabled(tc.getSelectionEnd() > tc.getSelectionStart());
        }
      });
      b.setEnabled(tc.getSelectionEnd() > tc.getSelectionStart());
    }
}

Began life as a copy of #1004936