Notification to moderators when administrative tasks are being carried out

[Clorith]

In relation with #1721, it is handy to avoid crossing the streams.

pipping has a plugin, ​https://github.com/pippinsplugins/bbPress-Topic-Lock, which sort of moves in that direction, the idea here is that instead of alerting you to another moderators presence in a topic (which may happen quite often), instead if a moderator is in the /moderate view, a warning is shown to any moderator capable user when viewing the topic in general (if this is an ajax action, or just a static warning when the topic is loaded will have to be thought of, perhaps a filter to switch ajax behavior on or of for this on heavy load sites?)

[johnjamesjacoby]

We've implemented WordPress core's _edit_lock approach in #3073, but I agree that we should do this once we have a moderator area for each user/forum/topic/reply.

I'd like to close this in favor of continuing the discussion happening on #1721. It's on my mind to do, and in the comments there, which should be sufficient to architect later.