Getting this function to work in more browsers than only ie....

Does anyone have a clue if I can get this function to work in Netscape and mozilla

Code:
<script language="javascript">
<!--
 function expand(listID) {
        if (listID.style.display=="none")
			{
				listID.style.display="";
			}
        else 
			{
				listID.style.display="none";
			}
}
 //--> </SCRIPT>
Thanks

Peanuts