[Typo3] External URL in menu

[Claudio]

I got some working code to display an icon in case a menu link is
actually an external URL page. I started from an example that I
found in the archive of this mailing list. 
Here it is:

NO {
  stdWrap.cObject = CASE
  stdWrap.cObject {
    key.field = doktype
    default = TEXT
    default.field = title
    default.typolink.parameter.data = field:uid
    default.typolink.ATagBeforeWrap=1
    default.typolink.wrap=|

    3 < .default
    3.typolink.ATagBeforeWrap=1
    3.typolink.wrap = |<img src="/fileadmin/images/extlink.gif"
    alt="External URL" /> 3.stdWrap.htmlSpecialChars = 1
  }
  doNotLinkIt = 1
  subst_elementUid = 1
  wrapItemAndSub = <li class="menu-l2-no">|</li>
} 

This does not make me completely happy, because I'd have preferred a
direct link to the final external URL, as I said in my first message. 
But, at least, it works.

Claudio