Forum posts list should show a 'solved' icon

Trying to help means regularly reading all unread forum threads. Even when they have some answers they could still need input.
However in some threads the OP is satisfied with the answers and the last post is something like "thank you" or "issue solved" or "ok I get it"...
Having the possibility to mark a thread as "solved" (or "closed" or "answered" whatever the name) would help the helpers !