function checkParent(src, dest) {
   while (src!=null) {
      if (src.tagName == dest) return src;
        src = src.parentElement;
    	}
    return null;
	}
function Menu() {     
    var open = event.srcElement;
    var el = checkParent(open, "LI");
    if (null!=el) {
       var pos = 0;
       for (var pos=0; pos<el.children.length; pos++) {
        if ("UL"==el.children[pos].tagName) break;
      }
	  if (pos==el.children.length) return;
    } else return;
		  
    el = el.children[pos];
    if ("UL"==el.tagName) {
     if (""==el.style.display) {
        el.style.display = "block";
      }
    else
      {
        el.style.display = "";
      }
    }
    event.cancelBubble = true;
}

document.onclick = Menu;