var activateMenu;
activateMenu = function(nav) {
	if(document.all && document.getElementById(nav).currentStyle){
     // only MSIE supports document.all
        var navroot = document.getElementById(nav);

        /* Get all the list items within the menu */
        var lis=navroot.getElementsByTagName("LI");
        for(i=0;i<lis.length;i++){
            /* If the LI has another menu level */
            if(lis[i].lastChild.tagName=="UL"){
                /* assign the function to the LI */
                lis[i].onmouseover=function(){
                    /* display the inner menu */
                    this.lastChild.style.display="block";
                }
                lis[i].onmouseout=function(){
                    this.lastChild.style.display="none";
                }
            }
        }
	}
}
window.onload=function(){
    // pass the function the id of the top level UL
    // remove one, when only using one menu
    activateMenu('menu_left');
}