Fully preloaded xml gallery

Ok this is less of a showcase more of i want your expert opinion on my coding thread, how i should improve it for this etc.
Basically what this gallery does:

Preloads all images at start, from xml, so you don’t have to re-preload everytime you view a different image. It does this by loading all the seperate images into one movieClip, and setting their visibility to false. When you select an image to view it sets the current image’s visibility to false and sets the selected image’s visibility to true.
All loaded images are re-scaled to fit the screen.
Can view and change image while other images are still preloading.
Can see which images are preloaded by availible thumbnails.

Ok, this is my first ever attempt at any kind of gallery + loading stuff from xml in flash and I didn’t look at any other xml gallery’s code before writing this so it’s from a complete newbie perspective (main resources were gotoAndLearn’s tutorials).
In the previous version I had the images changeing depths to set which image was visible. I thought this would be more processor intensive than just adjusting visibility though in my opinion it seems to have made performance slightly worse so i may change it back - anyone got any suggestions to why this is i’d appreciate them. Still it runs reasonably smooth for me, it’s not 100% tested though i have done some with real photos etc.
Lots of nasty placeholder graphics used atm so just ignore the looks.

Anyway appreciate you opinions!