function hover() {
    $$('.list-navigation li').each(function(element)
    {
        element.addEvents({
            'mouseenter': function(){
                this.addClass("hover");
            },
            'mouseleave': function(){
                this.removeClass("hover");
            }
        });
    });
}
if (window.addEventListener)
    window.addEventListener("load", hover, false);
else if (window.attachEvent)
    window.attachEvent("onload", hover);