static Rect shrinkRect(Rect r, int pixels default 1) {
  ret shrinkRect(pixels, pixels, r);
}

static Rect shrinkRect(int x, int y, Rect r) {
  ret new Rect(r.x+x, r.y+y, r.w-x*2, r.h-y*2);
}

static Rect shrinkRect(int x, int y, int w, int h, int pixels) {
  ret shrinkRect(Rect(x, y, w, h), pixels);
}