code: func WmIconSizeGet(xu *xgbutil.XUtil, win xproto.Window) (*IconSize, error) {
  	raw, err := xprop.PropValNums(xprop.GetProperty(xu, win, "WM_ICON_SIZE"))
  	if err != nil {
  		return nil, err
  	}
  	if len(raw) != 6 {
  		return nil,
  			fmt.Errorf("WmIconSize: Expected six integers in WM_ICON_SIZE "+
  				"property, but xgbutil found "+"%d in '%v'.", len(raw), raw)
  	}
  
  	return &IconSize{
  		MinWidth: raw[0], MinHeight: raw[1],
  		MaxWidth: raw[2], MaxHeight: raw[3],
  		WidthInc: raw[4], HeightInc: raw[5],
  	}, nil
  }
docs: // WM_ICON_SIZE get