Zlash

Zlash 1.0 is a decompiling / compiling program for ActionScript that supports .swf Flash files versions 6, 7, and 8. It is a multiplataform application for 32 bits Windows, Mac Os X, and shortly Linux will be included.

Zlash will let you capture the source code of any ActionScript, save it in a text file, edit it (with the embedded editor or your own preferred source code editor), recompile it, and create a new expanded .swf file, without the use of the master .fla project file.
Some of its characteristics are only accessible when buying a license to employ the complete software.
Now Zlash supports Flash files up to v 8.
Zlash supports UTF encoding of all strings in ActionScripts and allow font selection in the ActionScript editor to improve internationalization support.
Its features include:
·Decompile ActionScript contained in .swf files.
·Save ActionScript into text file. (registered version only)
·Recompile modified ActionScript (with an external editor or the included editor with color syntaxing).
·Decompile bytecode into assembly code readable by humans.
·Recompile bytecode from assembly code readable by humans.
·Save modified .swf file. (registered version only)