code: func SupportingWmCheckSet(xu *xgbutil.XUtil, win xproto.Window,
  	wmWin xproto.Window) error {
  
  	return xprop.ChangeProp32(xu, win, "_NET_SUPPORTING_WM_CHECK", "WINDOW",
  		uint(wmWin))
  }
docs: // _NET_SUPPORTING_WM_CHECK set