static BufferedImage renderTiledBackground(int w, int h) {
  BufferedImage img = newBufferedImage(w, h, Color.black);
  Graphics2D g = img.createGraphics();
  for (int x = 0; x < w; x += tileImage.getWidth())  
    for (int y = 0; y < h; y += tileImage.getHeight())
      g.drawImage(tileImage, x, y, this);  
    }
  };
  g.dispose();
  ret img;
}