private static boolean absolutelyUnknownKey (KeyEvent e) {
    return e.getKeyCode() == 0
           && e.getKeyChar() == KeyEvent.CHAR_UNDEFINED
           && e.getKeyLocation() == KeyEvent.KEY_LOCATION_UNKNOWN
           && e.getExtendedKeyCode() == 0;
  }
private static boolean absolutelyUnknownKey (KeyEvent e)