We have decided to try a feature of Discourse, the software powering this forum: bumping old open topics automatically.
We have enabled this option in two categories: #ask-here and #about-wikimedia-space:space-feature-requests. If you see one topic being bumped out of nowhere, this is why. We have set the bumping to one topic per day, the minimum allowed.
We believe that this feature will help us keeping these categories tidy, processing or updating open topics almost forgotten, assigning better tags to them, and so on.