Cool Drawing Board but need to limit where it draws

1

This drawing board is very cool!

However I’d need to be able to draw only on the board area (a 450 x 350 pixels area) instead on the whole movie…
Can someone tell me how to “tweak it?” :puzzle:

Here’s the fla:

http://www.soccerschool.com.ar/f/drawingBroadmx.zip