sclass HGridFinderGUI {
  BufferedImage img;
  ImageSurface is;
  JSlider slider;
  int ww = 10;
  
  *(BufferedImage *img) {}

  void show {
    is = showImage(img);
    slider = jliveSlider(1, 50, ww, voidfunc(Int value) {
      ww = value;
      split();
    });
    addToWindowWithMargin(is, sliderWithValueLabel(slider));
    split();
  }
  
  void split {
    new L<Rect> rects;
    int w = img.getWidth();
    for (int x = 0; x < w; x += ww)
      rects.add(new Rect(x, 0, min(ww, w-x), img.getHeight()));
    is.setImage(mergeImagePartsHorizontally(new RGBImage(img), rects));
  }
}