code: func (w *Window) Geometry() (xrect.Rect, error) {
  	geom, err := RawGeometry(w.X, xproto.Drawable(w.Id))
  	if err != nil {
  		return nil, err
  	}
  	w.Geom = geom
  	return geom, err
  }
docs: // Geometry retrieves an up-to-date version of the this window's geometry.
  // It also loads the geometry into the Geom member of Window.