Allow users with right to "edit comments" edit their own comments in closed tickets.

If you do not want to allow edit "closed" comments (that are dated before date of closing ticket), please make a date check: if comments is posted after date+time of closing ticket - this comment is editable (all comments, that are posted after date of closing ticket - editable).

Because sometimes it is required to post some comments to closed tickets, when they are linked with other tickets (to add some explaination or details). And you are able to post a new comment to a closed ticket, but not able to edit it. You will require to copy previous content, delete previous comment and add new one fixed. This is annoying.