code: func (b *Box) GetInnerRect() (int, int, int, int) {
  	if b.innerX >= 0 {
  		return b.innerX, b.innerY, b.innerWidth, b.innerHeight
  	}
  	x, y, width, height := b.GetRect()
  	if b.border {
  		x++
  		y++
  		width -= 2
  		height -= 2
  	}
  	return x + b.paddingLeft,
  		y + b.paddingTop,
  		width - b.paddingLeft - b.paddingRight,
  		height - b.paddingTop - b.paddingBottom
  }
docs: // GetInnerRect returns the position of the inner rectangle (x, y, width,
  // height), without the border and without any padding.