//requrie prototype
var Select = Class.create();
Select.prototype = {
	initialize: function () {
		this.current = 0;
	},
	select: function (id) {
		id = 'sub_'+id;
		if (this.current) {
			c = new Element.ClassNames(this.current);
			c.remove('on');
		}
		c = new Element.ClassNames(id);
		c.add('on');
		this.current = id;
	}
}
select = new Select();