Add menuclass-active class name to active menu items

When I style a menu item that has a class assigned by menuclass I can't style it's "active" state because the CSS selector .className1.className2{} is not cross-browser (IE doesn't see className1).
Example:
If I have a link that looks like <a href="/node" class="class_name"> and when active looks like <a href="/node" class="class_name active"> the code:

a.class_name{color:#fff;}
a.class_name.active{text-decoration:underline;}

Will not work on IE (at least 6, can't remember if 7 too), there the second deceleration will apply on all a.active elements.

Solution is simple: add class_name-active class too to the active element.