Alert box functionality in flash?

Hello everyone.

I’ve seen this technique done a few times and for the life of me I cannot figure it out. Basically, while in FLASH customized movieclip that looks like an alert box pops up and disables the entire movie behind it with a black transparent overlay. Where have I seen this, well, Macromedia uses it all the time on their site but mainly in their cart… thus I ran accross a different site the other day that also does the same thing.

[]On the following page that loads hit “I agree” at the bottom to enter the movie clip.
]Then once the clip loads look to the top right and choose “file” then “new” and automatically you’ll see what I’m talking about for they prompt you to do something when choosing “new”.
[/list]Any help would be appriciated.