I've currently wrote an app that receives a GCM message and stores it in a database then creates an alertDialog to show above any app what the new message is, the only problem i have is if a new message is received before the current alertDialog is closed you don't get to see the new message, if i sit and close each message its fine.
So i think what ive been trying is to ask 'is the alertDialog showing...if not show the message, if its already showing close it and open a new one with the new message'.
Does this sound feasible?
Cheers Mark
I would recommend using a notification rather than an alert dialog for showing incoming messages. The NotificationManager lets you set an id and tag when you post a notification. Then if you later post one with the same id and tag, the existing one will be updated.
On Lollipop (and newer) devices you can even get a similar effect to what you describe with the notification coming up on top of the current app using heads up notifications: http://developer.android.com/guide/topics/ui/notifiers/notifications.html#Heads-up