AS3 is there an event for when Android app is exiting on it's own?

Question

Ok, I made an app for Android. And when we push the middle button or back(lefthandside) button of Android phone, we all know that Android apps still runs in the background.
So my code is this:
the first line(addEventListener) is in a private function which runs as soon as you open the app.
    NativeApplication.nativeApplication.addEventListener(flash.events.Event.EXITING, onMyAppExit)
    private function onMyAppExit(event:flash.events.Event):void{
      trace("onMyAppExit is running");
      saveProgress();
Basically, I want saveProgress() to run when the app ACTUALLY exits from running in the background. I noticed that my app actually exits when I open another app like Candy Crush. I guess the Android OS exits apps automatically when the apps are not being used and when the app you are using takes a lot of RAM. However, my code only works when I run my app in AIR Debug Launcher(Mobile). I know that because I see the trace in the function in my output window when I click on the x button on the right corner of the app window. But when I connect my Android phone to the computer and then ---> AIR3.8 for Android settings ---> Publish, and then I "Begin Remote Debug Session", and on my Android phone, I open my app first, then open Candy Crush so that the Android OS automatically exits my app, I don't see the trace. So I finalized that the code didn't work on my phone.

Answer 1

i tried this too. but doesn't work
'(event:Event)'
private function onMyAppExit(event:Event):void{
and 'stage'
stage.nativeApplication.addEventListener(Event.CLOSING,onMyAppExit);