Bring to front

I've tested the Notification application.

 

It works really fine.

 

The question is quite simple:

 

I start this application, then press the "home" button which brings me to the home screen.

 

If I send a notification, the alert message is displayed but "behind" the home screen... so I have to press screen in order

to make it front again.

 

So, how could I achieve this:

 

bring to front the app when I receive an alert ?

 

Thanks

 

Nicolas, Toulouse, France