Notification window should show a preview of the message
Currently gajim notifies me like this: "Joe Smith has sent you a new message."
I think it would be more informative if the notification gave you a preview of the message in the popup, something like "Joe Smith: Hey, how is it going..."
I already now I'm getting a new message, since I'm being notified, so perhaps a more informative message in the notification would be friendlier.