Popup With 2 Tables, Slide Items Back and Forth

Hello,

I have a real easy question.  There's a pop up window.  It holds 2 tables with 2 arrows between them.  Each table has a list.  (Mine will be a list of names)
You use the arrows to transfer the items back and forth between each table. 

Here's a picture of one:  http://1.bp.blogspot.com/-CEEfqRh9dtk/T60NMv9ub8I/AAAAAAAACGo/Taz6Mcmb9yE/s1600/BCMRPU-interface.png

I can't think of the name of this.  Is there an AJAX thing for this?  Or is it all built by hand?

Using Visual Studio 2010.  ASP.NET VB

Jess