var W3CDOM = document.getElementById;
var openMenus = new Array();
var pressedNav = new Array();
var subMenus = new Array();
var timer;

subMenus[0] = 'overview';
subMenus[1] = 'courses';
subMenus[3] = 'visitors';
subMenus[4] = 'enrollment';

function getObj(idvalue) {
  return document.getElementById(idvalue);
}

function getObjStyle(idvalue) {
  return document.getElementById(idvalue).style;
}

function setTimer() {
  if (timer) clearTimeout(timer);
  timer = setTimeout('closeAllMenus(1)',2000);
}

function display() {
  if (timer) clearTimeout(timer);
  var num = this.number;
  if (num <= 8) menuLvl = 1;
  if (num > 8) menuLvl = 2;

  if (openMenus[menuLvl] && openMenus[menuLvl] == subMenus[num]) return;
  if (openMenus[menuLvl]) closeAllMenus(menuLvl);
  if (!subMenus[num]) {}
  else {
      menuToShow = getObjStyle(subMenus[num]);
      menuToShow.visibility = 'visible';
  }
  openMenus[menuLvl] = subMenus[num];
  if (this.className) return;
  this.className = 'over';
  if (pressedNav[menuLvl]) pressedNav[menuLvl].className = '';
  pressedNav[menuLvl] = this;
}

function closeAllMenus(lvl) {
  for (i=openMenus.length - 1; i>=lvl; i--) {
      if (openMenus[i]) {
          menuToHide = getObjStyle(openMenus[i]);
          menuToHide.visibility = 'hidden';
      }
      openMenus[i] = null;
      if (pressedNav[i]) {
      pressedNav[i].className = '';
      pressedNav[i] = null;
      }
  }
}

window.onload = function() {
  if (!W3CDOM) return;
  var navHolder = getObj('navbar');
  var navItems = navHolder.getElementsByTagName('a');
  for (i=0; i<navItems.length; i++) {
      navItems[i].onmouseover = display;
      navItems[i].onmouseout = setTimer;
      navItems[i].number = i;
  }
}