Instead, go get Flex Builder 3. It’s still in beta, but freely available and built on Eclipse with all the IDE-niceness that comes with that platform. Refactoring is a bit sketchy, and probably difficult to get right in a language like Actionscript, but otherwise it’s very well rounded. The best part is that Actionscript 3 comes with most of the good stuff from Ecmascript 4 (could someone sync the versions please?), features like packages, proper classes (as opposed to the prototype-voodoo) and optional, strong typing.