please include function showImageWithSelections.

static void onImageSurfaceHighlightChange(final ImageSurface is, final VF1<Rect> f) {
  final Var<Rect> highlighted = showImageWithSelections_highlighted;
  imageSurfaceOnMouseMove(is, new Runnable {
    Rect last;
    
    public void run() {
      if (eq(highlighted!, last)) ret;
      last = highlighted!;
      pcallF(f, last);
    }
  });
}