code: func WmStateGet(xu *xgbutil.XUtil, win xproto.Window) (*WmState, error) {
  	raw, err := xprop.PropValNums(xprop.GetProperty(xu, win, "WM_STATE"))
  	if err != nil {
  		return nil, err
  	}
  	if len(raw) != 2 {
  		return nil,
  			fmt.Errorf("WmState: Expected two integers in WM_STATE property "+
  				"but xgbutil found %d in '%v'.", len(raw), raw)
  	}
  
  	return &WmState{
  		State: raw[0],
  		Icon:  xproto.Window(raw[1]),
  	}, nil
  }
docs: // WM_STATE get