code: func (p *Pages) SendToBack(name string) *Pages {
  	for index, pg := range p.pages {
  		if pg.Name == name {
  			if index > 0 {
  				p.pages = append(append([]*page{pg}, p.pages[:index]...), p.pages[index+1:]...)
  			}
  			if pg.Visible && p.changed != nil {
  				p.changed()
  			}
  			break
  		}
  	}
  	if p.HasFocus() {
  		p.Focus(p.setFocus)
  	}
  	return p
  }
docs: // SendToBack changes the order of the pages such that the page with the given
  // name comes first, causing it to be drawn first with the next update (if
  // visible).