I have made a PlayheadNotifier class that I use to communicate with Flash's timeline.
Sometimes you want to execute a function only when a certain frame of animation is reached.

However, there is one caution -- what happen if the animation was intercepted and the frame was never reached? Your function will never get executed. If you are setting state information in that function, then your object will be in an incorrect state.

When coding in Flash, you must always be mindful that any code execution path that is tied to your playhead may be intercepted.