Chaotic Horde

Hello,

I’m trying to create a scroll bar for a dynamically generated group of movie clips.

A couple good examples of exactly what I’m looking for are right here:

Telus Smart Phones (In the top-right corner click "All Phones")
http://promo.telusmobility.com/smart…ctBrowserState

Shop Composition (on the bottom, select catagory, view all..)
https://www.shopcomposition.com/secure.aspx

These are both, functionally the exact same thing.

How would I go achieving an end product like this?

Thanks!