HoverMenu = Class.create({
  initialize: function(menuElement) {
    this.menuElement = menuElement;
    Event.observe(menuElement, 'mouseover', this.onMenuIn.bindAsEventListener(this));
    Event.observe(menuElement, 'mouseout', this.onMenuOut.bindAsEventListener(this));
  },
  onMenuIn: function(event) {
    $(this.menuElement).addClassName('hover'); 
  },
  onMenuOut: function(event) {
    $(this.menuElement).removeClassName('hover');
  }
});