sclass ScreenOverlay is AutoCloseable {
  JWindow window;
  Color bgColor = colorWithAlpha(Color.blue, 128);
  settable Rect bounds;
  settable bool hideOnMouseOver;
  
  void show() swing {
    if (window == null) {
      assertNotNull(+bounds);
      window = new JWindow;
      window.setBackground(bgColor);
      main setBounds(window, bounds);
      window.setAlwaysOnTop(true);
    
      if (hideOnMouseOver)
        addMouseListener(getContentPane(window), new MouseAdapter {
          @Override
          public void mouseEntered(MouseEvent e) {
            hide();
          }
        });
    }
    
    window.setVisible(true);
  }
  
  void hide aka close() swing {
    if (window == null) ret;
    window.setVisible(false);
  }
}