please include function showImage.

static ImageSurface showImage_centered(final BufferedImage img) {
  ret (ImageSurface) swing(func {
    ImageSurface is = new ImageSurface(img);
    JPanel panel = new JPanel(new GridBagLayout);
    panel.add(is);
    JFrame frame = showPackedFrame(new JScrollPane(panel));
    frameIcon(frame, showImage_defaultIcon);
    return is;
  });
}

static ImageSurface showImage_centered(final BufferedImage img, fS title) {
  ret setFrameTitle(showImage_centered(img), title);
}

static ImageSurface showImage_centered(S title, BufferedImage img) {
  ret showImage_centered(img, title);
}

static ImageSurface showImage_centered(S title, RGBImage img) {
  return showImage_centered(title, img.getBufferedImage());
}