Determine if the user deactivated your app via the home or lock button

distriqt.extension.application.deactivation.as

Application.init( APPLICATION_KEY );
if (Application.isSupported)
{
	Application.service.addEventListener( ApplicationStateEvent.DEACTIVATE, application_deactivateHandler );
}	

function application_deactivateHandler( event:ApplicationStateEvent ):void
{
	switch (event.code)
	{
		case ApplicationStateEvent.CODE_HOME:
			// home button was pressed
			break;
		
		case ApplicationStateEvent.CODE_LOCK:
			// lock button was pressed
			break;
	}
}

// com.distriqt.Application

I tried it but home and lock buttons still work. Should I describe anything into manifest related to this function?

This isn't designed to stop the operation but allow you to determine the method by which your application was deactivated.

http://airnativeextensions.com/extension/com.distriqt.Application