static ImageSurface showImageWithSelections(MakesBufferedImage img, final Cl<Rect> rects) {
  ret showImageWithSelections(img.getBufferedImage(), rects);
}

static ImageSurface showImageWithSelections(S title, BufferedImage img, Cl<Rect> rects) {
  ret frameTitle(title, showImageWithSelections(img, rects));
}

static ImageSurface showImageWithSelections(BufferedImage img, Cl<Rect> rects) {
  ret showImageWithSelections(img, null, rects);
}

static ImageSurface showImageWithSelections(BufferedImage img, Rect... rects) {
  ret showImageWithSelections(img, asList(rects));
}

// for callers to use
static Var<Rect> showImageWithSelections_highlighted;

static ImageSurface showImageWithSelections(BufferedImage img, ImageSurface _is, Cl<Rect> _rects) {
  final ImageSurface is = showImage(img, _is);
  final L<Rect> rects = sortRectsBySize(_rects);
  final new Var<Rect> highlighted;
  showImageWithSelections_highlighted = highlighted;
  is.overlay = voidfunc(Graphics2D g) {
    for (Rect r : rects)
      is.drawSelectionRect(g, r.getRectangle(), Color.blue, Color.white);
    if (highlighted.has())
      fillRect(g, scaleRect(highlighted!, is.getZoomX(), is.getZoomY()), new Color(0, 0, 0, 0x30)); // semi-transparent black
  };
  imageSurfaceOnMouseMove(is, voidfunc(Pt p) {
    repaintIf(is, setVarIfNeq(highlighted, smallestRectContaining(rects, p)));
  });
  
  is.repaint();
  ret is;
}