code: func WmPingExtra(xu *xgbutil.XUtil, win xproto.Window, response bool,
  	time xproto.Timestamp) error {
  
  	pingAtom, err := xprop.Atm(xu, "_NET_WM_PING")
  	if err != nil {
  		return err
  	}
  
  	var evWindow xproto.Window
  	if response {
  		evWindow = xu.RootWin()
  	} else {
  		evWindow = win
  	}
  
  	return ClientEvent(xu, evWindow, "WM_PROTOCOLS", int(pingAtom), int(time),
  		int(win))
  }
docs: // _NET_WM_PING req extra