After already searching the site for the answer to the question, I've found this:
Is it any way to run two instances of debuggers?
I need the Flash Professional CS5.5 version of the answer to this question.
Basically - I need to know if there's a way to debug 2 different .fla files in Adobe Flash Professional CS5.5 at the same time. One of them implements the Adobe AIR framework (for using the SocketServer class), the other is a standard AS3 project. It'd be nice if I could debug the client-server interaction easily using the IDE rather than using extensive means to do so.
Anyone have any ideas? Thanks.
This is not an answer to your question but a suggestion to take a different approach.
The Flash IDE and it's debugger are inadequate but for most trivial programs. Variable inspection and breakpoints work randomly and it's next to impossible to drill down into more complex objects. Flash IDE is all right for creating the visual resources for Flash programs but for any serious coding, it just falls on its face. The compiler included with the Flash IDE is also very poorly written and generates unoptimized code.
I'd suggest to switch over to using FlashDevelop - it's a free, open source IDE that runs on top of the Flex and Air SDKs and uses a better compiler that performs more optimizations. (You can mark functions for inlining, etc.) The debugger - while not Visual Studio - is much, much better than the IDE: breakpoints work and object properties can be inspected easily.
Because FlashDevelop is geared towards coding, you can create a project in it with multiple source files, define your resources and then compile to multiple platforms. Compilation is usually fast with hundreds of source files (don't import every type in every package) and you can do debug/release builds. If you can port your code from Flash to FlashDevelop, you'll have a much easier time managing your project.