Document Class Question

Hello all,

I have a question about the document class and hopefully someone can explain why the first frame in my fla file is being called twice.

I have a class RS_MovieClip; this class is just to extend functionality of the MovieClip class adding properties and methods I’m used to using.

public class RS_MovieClip extends MovieClip{
  //some properties and methods.

Now if I set the document class to RS_MovieClip and set the Base Class of a MovieClip in the library to RS_MovieClip.

Place an instance of “greenSquare” on the stage. Put a

trace("first frame");

on the first frame.

When I test movie I receive 2 traces.

Whats also really weird is that if I create a new symbol in the library exported as blueSquare, that just has a blue square in it. Then on the first frame put:

addChild(new blueSquare());

I get a blue square on the stage and in the greenSquare instance that is on the stage.

If someone could explain to me why this is happening I would greatly appreciate it.