static BufferedImage renderBackgroundPlusRoundedBoxes(int w, int h, BackgroundPlus<RoundedBoxWithColor> s) {
  BufferedImage bi = newBufferedImage(w, h, toColor(s.background));
  Graphics2D g = imageGraphics(bi);
  for (RoundedBoxWithColor e : s.things) {
    int x1 = min(e.a.x, e.b.x), y1 = min(e.a.y, e.b.y);
    int x2 = max(e.a.x, e.b.x), y2 = max(e.a.y, e.b.y);
    fillRoundedBox(g, x1, y1, x2-x1+1, y2-y1+1, e.roundness, toColor(e.color));
  }
  g.dispose();
  ret bi;
}

Began life as a copy of #1014969