Amit Gupta

pmcdotcom

If a post is being edited by another user, you get to know about it only when you open that particular post and the chances of accidentally overwriting the other user’s changes are there.
This plugin will highlight the posts that are being edited by other user(s) right on the post listing page in wp-admin without you having to open a post to find that out, thus removing any chance of you overwriting other user’s changes.
Github: https://github.com/Penske-Media-Corp/pmc-edit-lock-marker
WordPress.org plugin repo: https://plugins.svn.wordpress.org/pmc-edit-lock-marker/

PMC Edit Lock Marker

A plugin to mark the posts on wp-admin/edit.php page which are currently being edited by other users.

Bryan Petty

Disables automatic post locking so multiple users can open the same post in 
the administration panel.
Warning: Post locking was an addition to WordPress in order to prevent such 
bugs as overwritten autosaves (coming from multiple authors), and of course 
to prevent accidentally overwriting another user’s changes with older content. 
These are often never problems for many users, and you should likely be 
communicating with your fellow editors when making changes anyway. This plugin 
makes the choice of relying on the latter rather than post locking, so you 
may run into those problems again.

Disable Post Locking

Disables automatic post locking so multiple users can open the same post in the administration panel.

PMC Edit Lock Marker vs Disable Post Locking