Foren / Cotonti / Skins / Current class on ID problem

I'm using a jQuery lavalamp menu with the following HTML:

<div id="menu">
    <ul class="menu">
        <li><a href="index.php"><span>Home</span></a></li>
		
        <li id="school"><a href="#"><span>School</span></a>
            <div><ul>
                <li><a href="plug.php?e=contact"><span>Contact</span></a></li>
                <li><a href="#"><span>Organisation</span></a></li>
                <li><a href="#"><span>Membership</span></a></li>
                <li><a href="#"><span>Research</span></a></li>
            </ul></div>
        </li>
		
        <li id="newscat"><a href="page.php?c=newscat"><span>News</span></a>
            <div><ul>
                <li><a href="page.php?c=newscat"><span>Archive</span></a></li>
                <li><a href="#"><span>Activities</span></a></li>
                <li><a href="#"><span>Agenda</span></a></li>
                <li><a href="#"><span>Newsletter</span></a></li>
            </ul></div>
        </li>
		
        <li id="links"><a href="page.php?al=links"><span>Links</span></a></li>
    </ul>
</div>

I'm using ID's for every <li> item, and i've put in the custom.TPL files such as page.list.newscat.tpl the following JavaScript:

<script type="text/javascript">
var element = document.getElementById("newscat");
element.className = element.className + "current";
</script>

This works fine and applies the 'current' class to the according <li> menu item when that page is opened via the menu link.
The problem is though, that this does not work anymore when for example a page is being edited because the url then turns into 'page.php?m=edit&id=18'. Because of this the current class is lost..

How can I solve this?