NavBuilder = Class.create();
NavBuilder.build = function(el) {
    var defaultTab = document.body.className;
    var tabs = $('menu').select('.tab');
    tabs.each(function(i) {
        Object.extend(i, {
            activate: function() {
                this.mouseOverListener = this.onMouseOver.bindAsEventListener(this);
                Event.observe(this, "mouseover", this.mouseOverListener);
            },
            onMouseOver: function(e) {
                document.body.className=this.className;
            }
        }).activate();
    });
    /*
    Object.extend(el, {
        activate: function() {
            this.mouseOutListener = this.onMouseOutOfNav.bindAsEventListener(this);
            Event.observe(this, "mouseout", this.mouseOutListener);
        },
        onMouseOutOfNav: function(e) {
            var rt = (e.relatedTarget) ? e.relatedTarget : e.toElement;
            if (rt == null || (rt != el && !$(rt).descendantOf(el)))
                document.body.className=defaultTab;
        }
    }).activate();*/
};
NavBuilder.build($('nav'));