code: func (v *Surface) MarkDirtyRectangle(x, y, width, height int) {
  	C.cairo_surface_mark_dirty_rectangle(v.native(), C.int(x), C.int(y),
  		C.int(width), C.int(height))
  }
docs: // MarkDirtyRectangle is a wrapper around cairo_surface_mark_dirty_rectangle().