bbPress Topic Lock is a free extension for bbPress that warns forum moderators if another moderator is currently viewing the same topic.
WordPress core has a Post Locking system that warns users if another user is editing the same post. In WordPress 3.6, this system was dramatically improved by utilizing the Heartbeat API.
I decided to take this same idea and extend it over to bbPress forums so that moderators could know when another moderator was viewing/answering the same topic, in an attempt to help prevent duplicate replies.
Using the WordPress Heartbeat API, forum topics are now “locked” by the first moderator to view it. If another moderator loads the topic while the first moderator is still viewing it, a dialog is displayed:
While it’s not a true “lock” system, as moderators can choose to ignore the notice, it still serves the same purpose of helping alleviate double posting by multiple moderators.