startList = function() {
    navRoot = document.getElementById("DropdownMenu");
    showNodes(navRoot);
}

function showNodes(navRoot) {
    for (i=0; i<navRoot.childNodes.length; i++) {
        node = navRoot.childNodes[i];

        if (node.nodeName=="LI") {
            node.onmouseover=function() {
                this.className+=" hover";
            
                for (i=0; i<this.childNodes.length; i++) {
                    subnode = this.childNodes[i];
                    if (subnode.nodeName=="UL") {
                        showNodes(subnode);
                    }
                }

            }// function

            node.onmouseout=function() {
                this.className=this.className.replace
                (" hover", "");
            }// function

        }// if
    }// for
}

window.onload=startList;