FlashDevelop is best free editor for ActionScript projects. I absolutly love it. There are many things that helps me in everyday work.
Now it comes 3.0.0 beta 3 release with some new features which will surely be usefull.
* Quick Find tool added, similar to one in Firefox
* Start page plugin added (contributed by Mike McMullin)
* Flex debugger integrated for trace captures (no more FlashConnect)
* Completion is now “always on”, as in Visual Studio (configure in AScompletion settings)
Some things done:
* Revised installer texts and selected components
* Improved local code formater (enable from ASCompletion settings)
* Many general completion and UI fixes
Read more and download from http://www.flashdevelop.org/community/viewtopic.php?t=1935
Great news is also that
“Also we are pleased to announce that Alessandro “sepiroth” Crugnola has recently joined the team – he already produced a fair amount of additional plugins!”