..., but the core is encripted with eval.
I grabbed the script and searched for eval, not a sign of it.... ..
However, I did spot this.
// "Tabs & Slides In Content Items" Plugin for Joomla! 1.0.x - Version 2.2
// License: http://www.gnu.org/copyleft/gpl.html
// Authors: Fotis Evangelou - George Chouliaras
// Copyright (c) 2006-2007 JoomlaWorks.gr - http://www.joomlaworks.gr
// Project page at http://www.joomlaworks.gr - Demos at http://demo.joomlaworks.gr
// ***Last update: January 14th, 2007***
if that helps you, you now know where to go to get the framework that helps that sites menu work.