static BufferedImage renderBackgroundPlusLines_withHints(int w, int h, BackgroundPlus<LineWithColor> s) {
  BufferedImage bi = renderBackgroundPlusLines(w, h, s);
  RGBImage img = new RGBImage(bi);
  for (LineWithColor e : s.things)
    for (Line l : s.lines)
      rgbMarkPoints(img, toColor(e.color), 1, e.a, e.b);
  ret rgbUncache(img);
}