function buildsubmenus(){
  var ultags=document.getElementById("menu_nav").getElementsByTagName("ul");
  var lengte = ultags.length;
    for (var t=0; t<ultags.length; t++){
		//alert(ultags[t].parentNode.parentNode.id);
	    ultags[t].parentNode.getElementsByTagName("a")[0].className="subfolderstyle"
			if (ultags[t].parentNode.parentNode.id=='menu_nav') //if this is a first level submenu
				ultags[t].style.left=ultags[t].parentNode.offsetWidth+"px" //dynamically position first level submenus to be width of main menu item
			else //else if this is a sub level submenu (ul)
		//ultags[t].style.left=ultags[t-1].getElementsByTagName("a")[0].offsetWidth+"px" //position menu to the right of menu item that activated it
				// ST: bovenstaande positionering geeft een fout. er moet iets hier gebeuren, anders geen subuitklap
				ultags[t].style.left="170px";
				//alert("positie");
	    ultags[t].parentNode.onmouseover=function(){
	    this.getElementsByTagName("ul")[0].style.display="block"
	    }
	    ultags[t].parentNode.onmouseout=function(){
	    this.getElementsByTagName("ul")[0].style.display="none"
	    }
    }
	for (var t=ultags.length-1; t>-1; t--){ //loop through all sub menus again, and use "display:none" to hide menus (to prevent possible page scrollbars
	ultags[t].style.visibility="visible"
	ultags[t].style.display="none"
	}
}

if (window.addEventListener)
window.addEventListener("load", buildsubmenus, false)
else if (window.attachEvent)
window.attachEvent("onload", buildsubmenus)