extra class for <li>

Hi, I have changed the line 639 (the last 6.x .module) in my installation into:
$extra_class[] = 'menu-href-' . str_replace('/','-',$items[$key]['link']['href']);
instead of link id (which I usually do not know) I use the link (which I do know), so I may style it with an image. It may help others as well(?)
Best,
Michal