Mask between XML image gallery?[mx2004]

I’ve been playing around with the gallery in this tutorial. http://www.kirupa.com/developer/mx2004/xml_flash_photogallery.htm

I was wonderig though, if anyone knows a way to create a mask transition between each loaded image. I fiddled around with it a bit, but can’t seem to come up with anything, and I was wondering if it was even possible?
Anyone know? Thanks:)