code: func findIconEwmh(X *xgbutil.XUtil, wid xproto.Window,
  	width, height int) (*Image, error) {
  
  	icons, err := ewmh.WmIconGet(X, wid)
  	if err != nil {
  		return nil, err
  	}
  
  	icon := FindBestEwmhIcon(width, height, icons)
  	if icon == nil {
  		return nil, fmt.Errorf("Could not find any _NET_WM_ICON icon.")
  	}
  
  	return NewEwmhIcon(X, icon), nil
  }
docs: // findIconEwmh helps FindIcon by trying to return an ewmh-style icon that is
  // closest to the preferred size specified.