var SlideList = new Class({
initialize: function(menu, options) {
	this.setOptions(this.getOptions(), options);
 
	this.menu = $(menu), this.current = this.menu.getElement('li.current');
 
	this.menu.getElements('li').each(function(item){
		item.addEvent('mouseover', function(){ this.moveBg(item); }.bind(this));
		item.addEvent('mouseout', function(){ this.moveBg(this.current); }.bind(this));
		item.addEvent('click', function(event){ this.clickItem(event, item); }.bind(this));
	}.bind(this));
 
	this.back = new Element('li').addClass('background').adopt(new Element('div').addClass('left')).injectInside(this.menu);
	this.back.fx = this.back.effects(this.options);
	if(this.current) this.setCurrent(this.current);
},
 
setCurrent: function(el, effect){
	this.back.setStyles({
		left: (el.offsetLeft)+'px', width: (el.offsetWidth)+'px'
	});
	
	(effect) ? this.back.effect('opacity').set(0).start(1) : this.back.setOpacity(1);
	this.current = el;
},
 
getOptions: function(){
	return {
		transition: Fx.Transitions.sineInOut,
		duration: 500, 
		wait: false,
		onClick: Class.empty
	};
},
 
clickItem: function(event, item) {
	if(!this.current) this.setCurrent(item, true);
	this.current = item;
	this.options.onClick(new Event(event), item);
},
 
moveBg: function(to) {
	
	if(!this.current) return;
	
	this.back.fx.custom({
		left : [this.back.offsetLeft, to.offsetLeft],
		width: [this.back.offsetWidth, to.offsetWidth]
	});
}
});
 
SlideList.implement(new Options);