The following scenario frequently happens: member $M_1$ answers a question, but he makes a typo that member $M_2$ points out. So $M_2$ leaves a comment, $M_1$ corrects the answer. If this correction is made when $M_2$ is not logged in, the comment may remain for a while (I personally have a lot of such comments posts, but especially when I play the role of $M_1$).

What I suggest is the following: in the same way as we can choose whether an answer is community-wiki or not, we can show whether a comment is NLR (no longer relevant) or not by picking a square, with the following features:

• the comment can be deleted by $M_1$ once the correction is done;
• it is automatically deleted after a while (for example when $M_1$ thanks $M_2$ for the edit).

It can also concern questions. For example when an user sees a typo in the question, or asks for a precision, which will (normally) come.

• Related (but not duplicate): meta.math.stackexchange.com/questions/7033/… – apnorton Mar 3 '13 at 17:13
• What if you point out an error and malicious answerer makes a small change to his or her's answer but doesn't fix the error and then deletes your comment? – JSchlather Mar 3 '13 at 17:14
• @JSchlather If he doesn't fix the error, it is probably because he didn't red $M_2$'s comment. I think in this case, after an edit, $M_1$ have the choice to delete $M_2$'s comment or not. – Davide Giraudo Mar 3 '13 at 17:17
• @DavideGiraudo I was commenting on how something like this could be abused to cover up mistakes. I doubt it'd happen very frequently, but it'd be something to keep in mind. – JSchlather Mar 3 '13 at 17:20
• Since I flagged several of those comments today, may I ask if I should stop doin' this? It's just that these comments really feel obsolete-like... – draks ... Mar 3 '13 at 17:49
• The trouble is, X makes a mistake, Y points it out in a comment, X corrects the mistake and leaves a comment thanking Y, Y deletes her comment and leaves a new comment saying "I've deleted my comment; you can delete your thanks", X deletes his thanks and leaves a new comment saying "I've deleted my thanks, now you can delete your recent comment" and so on ad infinitum. – Gerry Myerson Mar 3 '13 at 23:19
• @GerryMyerson This scenario can happen with the current features. And this will be prevented by the second bullet in the OP. – Davide Giraudo Mar 4 '13 at 12:43
• would it be possible to add a flag or button by which $M_2$ can indicate that his comment is No Longer Relevant? – Vincent Tjeng Mar 5 '13 at 6:59
• There's already a feature whereby a user can flag a comment as "obsolete", and the moderators will look at it and often delete it. Since that system seems to be working, why do we need a new system to accomplish the same thing? – MJD Mar 5 '13 at 7:21
• @MJD I wasn't aware of this feature. So, my question is no longer relevant... – Davide Giraudo Mar 5 '13 at 8:07
• @MJD I can't seem to flag my own comment as obsolete though - and will a comment flagged as obsolete be shown as such to the community or simply removed? that could lead to a bit of a disjointed conversation. – Vincent Tjeng Mar 6 '13 at 3:40