function toggleMenu(obj){
	var clickedMenu = document.getElementById(obj);
  // Find parent lists
  var parents = [];
  var parent = clickedMenu;
  var p = -1;
 	while(parent.parentNode.id != "main_menu") {
 	  parent = parent.parentNode;
	  if (parent.nodeName == 'UL') {
      parents[++p] = parent.id;
      }
 	  }
  // Clear any menu items tagged as current
	var li = document.getElementById("main_menu").getElementsByTagName("li");
	var str;
	for (var i=0; i<li.length; i++) {
    str = li[i].className;
    str2 = str.replace(/ current/g,"");
    li[i].className = str2;
  	}
	// Display/hide menus
	var subMenus = document.getElementById("main_menu").getElementsByTagName("ul");
	if (clickedMenu.style.display != "block") { // Display sub-menu
    // Hide other menus
		for (var i=0; i<subMenus.length; i++) { // Hide other menus...
      toDisplay = "none";
      current = "";
      for (var j=0; j <= p; j++) { // ...except for parent menus
        if (parents[j] == subMenus[i].id) {
          toDisplay = "block";
          current = " current";
          }
        }
      subMenus[i].style.display = toDisplay;
      subMenus[i].parentNode.className = subMenus[i].parentNode.className + current;
      }
    // Display clicked-on menu & set to current
    clickedMenu.style.display = "block";
    clickedMenu.parentNode.className = clickedMenu.parentNode.className + " current";
	  }
  else {
		clickedMenu.style.display = "none";
	  }
  }