We need to perform a small amount of clean-up code on app exit but do not have a good mechanism to detect when the the app is closed.
We have experimented with numerous techniques, such as binding a function to the standard window 'unload' event, but have not been successful.
Adding support for blackberry.app.event.onExit (as is available on the WebWorks smartphone platform) would be ideal.
Sorry Michael, this posting should not have gone this long without a response.
Unfortunately I also don't have a solution to share. AIR does not have an 'exit' method to bind a JS extension to, and as you've mentioned the window 'unload' event does not fire as expected when the app is closed.
It still may be possible through an event that may be captured from the Tablet OS, however the solution is yet unknown.
I need this as well