code: func WmFullscreenMonitorsGet(xu *xgbutil.XUtil,
  	win xproto.Window) (*WmFullscreenMonitors, error) {
  
  	raw, err := xprop.PropValNums(
  		xprop.GetProperty(xu, win, "_NET_WM_FULLSCREEN_MONITORS"))
  	if err != nil {
  		return nil, err
  	}
  
  	return &WmFullscreenMonitors{
  		Top:    raw[0],
  		Bottom: raw[1],
  		Left:   raw[2],
  		Right:  raw[3],
  	}, nil
  }
docs: // _NET_WM_FULLSCREEN_MONITORS get