var MainMenu  = new Class ({
  initialize : function () {
    root = this;
    var mainmenu = $('mainmenu');
    var item = mainmenu.getFirst();
    for( i = 0; item != null; i++) {
        var subitem = $('sub'+item.id);
        if(subitem != null) {
          subitem.setStyle('display','none');
          item.addEvent('mouseenter', function () {
            root.display($('sub'+this.id));
          });
          item.addEvent('mouseleave', function () {
            root.hide($('sub'+this.id));
          });
        }
        item = item.getNext();
    }
  },
  display: function (el) {
    el.setStyle('display', 'block');
  }, 
  hide: function (el) {
    el.setStyle('display', 'none');
  }
});

var myMainMenu = null;
window.addEvent('domready', function(){
  myMainMenu = new MainMenu();
});