static JFrame showFullScreen(JComponent c) {
  ret showFullScreen(defaultFrameTitle(), c);
}

static JFrame showFullScreen(fS title, final JComponent c) {
  ret (JFrame) swingAndWait(func {
    GraphicsDevice gd = GraphicsEnvironment.getLocalGraphicsEnvironment()
      .getDefaultScreenDevice();
    if (!gd.isFullScreenSupported())
      fail("No full-screen mode supported!");
    bool dec = JFrame.isDefaultLookAndFeelDecorated();
    if (dec) JFrame.setDefaultLookAndFeelDecorated(false);
    final JFrame window = new JFrame(title);
    window.setUndecorated(true);
    if (dec) JFrame.setDefaultLookAndFeelDecorated(true);
    registerEscape(window, r { disposeWindow(window) });
    window.add(wrap(c));
    gd.setFullScreenWindow(window);
    
    // Only this hides the task bar in Peppermint Linux w/Substance
    for (int i = 100; i <= 1000; i += 100)
      awtLater(i, r { window.toFront() });
    
    ret window;
  });
}

Began life as a copy of #1004497