concept G22MaskSize {
  int width = g22defaultMaskSize(), height = g22defaultMaskSize();
  
  *(int widthHeight) {
    width = height = widthHeight;
  }
  
  bool square() { ret width == height; }
  
  toString {
    ret spaceCombine("Mask Size",
      square()
        ? width + "²"
        : width + "*" + height); }
}