[Moo] Barack Slideshow for 1.2.3+?

[Ryan Florence]

I'm goofing around with devthought's barack slideshow (http://devthought.com/projects/mootools/barackslideshow/ 
) but when I simply include the script in mootools 1.2.3 without even  
implementing it in my page I get this error:

  TypeError: Result of expression 'F' [undefined] is not an object.   
-- mootools-1.2.3-core.js:1099

At line 1099 is in core is:

  new Native({name: 'Class', initialize: Class}).extend({

        instantiate: function(F){
                F._prototyping = true;                <--- 1099
                var proto = new F;
                delete F._prototyping;
                return proto;
        },

Any tips on getting this thing working with 1.2.3?