Title says it all. Please consider adding a mechanism that blocks other users from starting an edit on a post if someone's already editing it.
Edit-locking is a sticky subject in computing. We used to have an FTP server that allowed users to lock files while they worked on them from Dreamweaver. That's all great until some nonce opens up the most important file and then goes for lunch, locking their PC. Locks expired after an hour of inactivity but it basically cost us a lot of effort (and one staff member's job).
If people wanted to be evil, they could post something offensive and lock it for editing. We'd normally edit the post as well as deleting it but outright edit-locking would stop us doing that.
In short, I don't think I could ever be happy with outright edit-locking but I do have some counter suggestions (combinations might work too):
Make the edit screen "live". Used Google Docs' word processor in collaboration-mode recently? You should! It's amazing. It was based on EtherPad and multiple people can edit at once and all people see the changes about 40ms after they happen. It's amazing to watch 10 people burrow away on a document at once.
This single point is such a good fix that it would counter-act the need for my other points entirely. If done well, this could solve all the problems... And probably hasten in world peace too.
Notify all editors when other people are editing. The edit page should poll the server to check who is editing. This way people might hold off if their edit is more trivial. Plus you could see if the owner of the post is doing work to it.
Merge edits better. If PersonA and PersonB both open a post for editing at roughly the same time, PersonA saves and then the PersonB saves different changes, PersonB should be alerted. They should see a diff between the post when they opened it, the current post (with PersonA's changes) and their own additions.
For bonus marks, it would be nice to mix-and-match parts. PersonB might want to drop some of their edits if they thought PersonA did a better job on the first paragraph, or thought the tag improvements were more relevant.
Notify mods and trusted users of edit conflicts. We [mods] get lots of notifications as it is, but sometimes when you wipe out somebody else's edits, you don't know you've done anything.
If two edits are made from the same version at roughly the same time, trusted editors should be prompted to fly in and clean up. This notification should disappear as soon as one editor goes in to fix it (or you'll get second-generation conflicts!)
A recent change we made is that the longer body edit has priority. So if you are editing a post at the same time as another user:
- if one of you changes title, and the other does not: title is merged
- if one of you changes tags, and the other does not: tags are merged
- if both of you change body: the longer body edit (the diff length) has priority and will win, assuming it is longer by some non-trivial amount.