Addon for Locking a Thread with Prefix?

Hey everyone,
Is there an addon that automatically locks a thread when a certain prefix is selected? So if I had two thread prefixes "Open" and "Closed" and a user chose the prefix "Closed", I would want the thread to auto-lock.

Thanks! :)
That might work, but I forgot to mention that it only needs to occur in one forum. Kind of like a support forum. When a situation is resolved, the member can mark it as solved. In this case, I need the thread to lock in that forum without providing a regular member full moderation access in other forums.