Ender22 You need to create a document provider in the manifest that says you serve/receive files. You then need to implement a class and about 4 methods, after that testing. 🙂
It's complicated but not complicated. 🙂 The idea is now all public directories from an app's perspective are in a sandbox.
This means that all files your app created in the public area, will now be in no mans land until you create a root provider so you can access it. This is where I am not entirely sure how AIR will handle this change under the covers.
It's a lot more information to fully implement but this is the general gist.
EDIT: I am being intentionally vague on purpose here, this is something a dev should own if used.