code: func (p *WebPage) ClipRect() (Rect, error) {
  	var resp struct {
  		Value rectJSON `json:"value"`
  	}
  	if err := p.ref.process.doJSON("POST", "/webpage/ClipRect", map[string]interface{}{"ref": p.ref.id}, &resp); err != nil {
  		return Rect{}, err
  	}
  	return Rect{
  		Top:    resp.Value.Top,
  		Left:   resp.Value.Left,
  		Width:  resp.Value.Width,
  		Height: resp.Value.Height,
  	}, nil
  }
docs: // ClipRect returns the clipping rectangle used when rendering.
  // Returns nil if no clipping rectangle is set.