code: func ActiveWindowReqExtra(xu *xgbutil.XUtil, win xproto.Window, source int,
  	time xproto.Timestamp, currentActive xproto.Window) error {
  
  	return ClientEvent(xu, win, "_NET_ACTIVE_WINDOW", source, int(time),
  		int(currentActive))
  }
docs: // _NET_ACTIVE_WINDOW req extra