Problem accessing a property

Hello All
I have downoaded a gallery file from this forum a while ago ( i can not even remember exactly where …) , and today i started to tweek a bit with the graphics…draging and opacity… small things.
I have a problem there, to hide the menu, or more accurate, i do not know how to access it (syntex problem ??)
What i want, if you will look at the file, is for the small red button on the right of “drag me” to change the opacit of the thumbs ( to 0 or 100 ) .
I tried directly or through masking … but none worked.
I may seem calm here - but i am getting really crazy over it :puzzle:.

Someone have an idea how to access it ?

file is here :
http://www.magmalab.net/cgtalk/20060429.kirupa.problem.zip

Swf is here

screencap here

There was some problem with the links … now it should be ok.