!7

p-awt {
  new JWindow f;
  f.setAlwaysOnTop(true);
  f.setBackground(new Color(0,255,0,0));
  f.setSize(512, 512);
  f.add(new JPanel {
    protected void paintComponent(Graphics g) {
      g.setColor(Color.RED);
      g.drawRect(0, 0, 511, 511);
    }
  });
  f.setLocationRelativeTo(null);
  f.setVisible(true);
}