If you use the "Active topics" feature to read a new topic in a forum then go back to the forum homepage, the forum is still flagged with new topics.

Steps to reproduce :

- Visit the homepage of the forum

- Open the active topics page

- Click a new topic in a forum (if the topic is the only new active topic in this forum)

- Read the last message

- Go back to the homepage : the forum is still flagged as "new"

- Click the forum : there is no topics marked as "new"

- Go back to the homepage : the forum is now marked as read

Solution :

When visiting a topic, update the forum flag if this subject is the only unread topic for this forum