When writing mobile applications over Flex 4.5.1, your application may be running in the background, even when pressing the back or home buttons on your device. This may become a problem if your application is doing things using timers, making server calls etc.
You can listen for Event.DEACTIVATE and Event.Activate events and stop or restart whatever is running in the background if you need to.
You do this over the NativeApplication, like:
NativeApplication.nativeApplication.addEventListener(Event.DEACTIVATE, appExitingHandler, false, 0, true);
NativeApplication.nativeApplication.addEventListener(Event.ACTIVATE, appinvokeHandler, false, 0, true);
NativeApplication.nativeApplication.addEventListener(KeyboardEvent.KEY_DOWN, handleKeys, false, 0, true);
In the handleKeys function you can check if the keyCode == Keyboard.BACK.
