Prevent the rest of the buttons "active"

programming flash
1

I am following this tutorial : http://www.kirupa.com/developer/mx2004/transitions.htm successfully.

How can I prevent the rest of the buttons “active” when the first movie is on the process of loading? In other word : How can I make the rest of button “active” ONLY until the first movie finished being loaded?

I’ve been seraching this forum, I thought the answer must be burried in tha vault…

Thanks