Topics get locked for some time (default is one hour) whenever a user edits, previews or saves a topic. This is to prevent simultaneous topic updates. There is a lock warning if another users tries to edit a topic while the lock is still on.

You can reset the lock by checking the "Unlock topic" checkbox in preview. This is a way to let other people know that you are done with your editing. **_Note:_** Please remember **not** to go back in your browser in case you checked the box and after that you decide to do more changes to the topic. Instead press the **Edit** link to re-edit your page.