It's the weirdest experience to see someone aggressively defend free software on the adobe.com website with Oracle as the target.
And there is at least one open source IDE that uses it: http://en.wikipedia.org/wiki/FlashDevelop
Also, the main part of the Flash Player is open source: http://en.wikipedia.org/wiki/Tamarin_%28JavaScript_engine%29
And if I understand it correctly, the only reason it's not is due to licensing and patent stuff that is out of the control of Adobe.
I mean, come ON! A plugin for freakin' word-wrap?!
You need to install a plugin to enable this. Granted, this is a limitation of the underlying Eclipse on which it is built, but I was using Flex Builder, not Eclipse, so my beef stands.
Citations: http://forums.adobe.com/thread/451245, http://www.communitymx.com/abstract.cfm?cid=E0D9F