def grid(box, draw)
      x, y, w, h = box.x, box.y, box.width, box.height
      use_cairo do |cc|
        (x..@width + w).step(w)  { |ix| line_xy(ix, y - @height, ix, @height + y, draw) }
        (y..@height + h).step(h) { |iy| line_xy(x - @width, iy, @width + x, iy, draw) }
      end
    end
def grid(box, draw)
      x, y, w, h = box.x, box.y, box.width, box.height
      use_cairo do |cc|
        (x..@width + w).step(w)  { |ix| line_xy(ix, y - @height, ix, @height + y, draw) }
        (y..@height + h).step(h) { |iy| line_xy(x - @width, iy, @width + x, iy, draw) }
      end
    end
:nodoc:
 @api private