window.addEvent('domready', function(){
  $('mainNav').getChildren('li').each( function (item, index) {
    item.addEvent('mouseenter', function () {                                           
      if (this.getElements('ul')[0]) {
        this.getElements('ul')[0].tween('display','block');
      }
    }.bind(item) );
    item.addEvent('mouseleave', function () {
      if (this.getElements('ul')[0]) {
        this.getElements('ul')[0].tween('display','none'); 
      }
    }.bind(item));
                                         
    item.getElements('ul li').each( function (item2, index2) {
      item2.addEvent('mouseenter', function () {                                           
        if (this.getElements('ul')[0]) {
          this.getElements('ul')[0].tween('display','block');
        }
      }.bind(item2));
      item2.addEvent('mouseleave', function () {                                        
        if (this.getElements('ul')[0]) {
          this.getElements('ul')[0].tween('display','none'); 
        }
      }.bind(item2));
    });
  });
  
  
});