buttons

http://www.nitras.be/tutorials/tutorial.html

onRelease = function(){

// return to default
if (selectedMovie != this){
selectedMovie.enabled = true;
}
// disabled selected button
selectedMovie = this
this.enabled = false;

}

helix class

http://www.gotoandlearnforum.com/viewtopic.php?f=12&t=5768

papervision

http://labs.blitzagency.com/?p=93

circle

http://www.gotoandlearnforum.com/viewtopic.php?f=28&t=16008