The switch from Actionscript 2.0 to Actionscript 3.0 saw many changes, as we all know. Some were superficial or minor, like removing underscores from certain properties. So _alpha became alpha. The range of alpha became 0 to 1 (formerly 0 to 100). These are among the small changes. Other changes were more extensive; some much more. Of all the changes, the two biggest ones were undoubtedly the display list and the event model. In fact, if you can master these two aspects of Actionscript 3.0, the remainder should be relatively easy.