I remember back in the days of Flash 5 and 6 where you had to write everything from scratch. Things like easing (Tweening) and physics all needed to be coded and modified by hand. Usually you would need to look at someone else’s source files, gut out what you think you needed and change the code to fit your needs. Not that we still don’t do that now to an extent. Back then there were no classes as we know of them today, just a bunch of functions (prototypes) in the first frame of your movie that you would call globally. If you were really fancy you would have an external AS file that would get included. I remember in Flash 7 it being so hard to get out of the old practices and start working more Object Oriented with true classes. Thank God that with the maturity of ActionScript the options are wide open. Developers build for reusability and even create API’s that facillitate life. PaperVision, APE, Box2D, Caurina Tweener… imagine where we would be if these technologies weren’t out there for us to use. This is only my take on it, others I’m sure had different experiences. I can only speak for myself. Stay tuned, I have more physics tutorials coming!