static JWindow showFullScreen_jwindow(JComponent c) {
  ret showFullScreen_jwindow(defaultFrameTitle(), c);
}

static JWindow showFullScreen_jwindow(fS title, final JComponent c) {
  ret (JWindow) swingAndWait(func {
    GraphicsDevice gd = GraphicsEnvironment.getLocalGraphicsEnvironment()
      .getDefaultScreenDevice();
    if (!gd.isFullScreenSupported())
      fail("No full-screen mode supported!");
    final JWindow window = new(title);
    registerEscape(window, r { disposeWindow(window) });
    window.add(wrap(c));
    gd.setFullScreenWindow(window);
    ret window;
  });
}