code: func WmSyncRequestCounterSet(xu *xgbutil.XUtil, win xproto.Window,
  	counter uint) error {
  
  	return xprop.ChangeProp32(xu, win, "_NET_WM_SYNC_REQUEST_COUNTER",
  		"CARDINAL", counter)
  }
docs: // _NET_WM_SYNC_REQUEST_COUNTER set
  // I'm pretty sure this needs 64 bit integers, but I'm not quite sure
  // how to go about that yet. Any ideas?