XML/Flash Gallery - Adding Thumbs Question

[COLOR=Black]I’m sure the answer is embarassingly simple - - -[/COLOR]

http://www.kirupa.com/developer/mx2004/thumbnails.htm

I am pretty new to flash design, but all of the tutorials here are helping me progress rapidly.

[COLOR=RoyalBlue]My question is, if I wanted to make the thumbnails in the above tutorial scroll up and down rather than from left to right, what would I do differently?[/COLOR]

The help is much appreciated. Thanks!