Hello everyone!
phpBB3 Forum code base can be quite confusing at times (like the Outbox vs. Sent Messages).
New messages (as in "unread") will also look not very different from normal ones and can get easily overlooked.
I made a few changes to improve this.
When you're all good, the top status bar will show: 0 new messages
If you get a new one and haven't opened it yet: 1 new message
If you do visit your Private Message box it will now show as
.Until you actually click and open it, status will be: 0 new messages | 1 unread message
After opening it (the sender will see it move from his/her Outbox to Sent), it will be displayed as
I hope this will help a bit!
Julien