function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}

var startList = function(myE) {
if (document.all&&document.getElementById) {
	if(document.getElementById(myE)){
		var navRoot = document.getElementById(myE);
		
		for (var i = 0; i < navRoot.childNodes.length; i++) {
		node = navRoot.childNodes[i];
		if (node.nodeName == "LI") {
		node.onmouseover=function() {
		this.className+=" over";
		  }
		  node.onmouseout=function() {
		  this.className=this.className.replace(" over", "");
		   }
		   }
		  }
		 }
}
}

addLoadEvent(function() {startList("mainnav")});