That feature of the table of contents can only work temporarily, for as long as there's activity within 24 hours.

Even though it's implicit in the design, I hadn't anticipated this ramification of it. This could be a bit confusing, having threads bob to the surface for a while then sink without a trace. A fix is possible, I think. Right now threads are cataloged by two fields, creation date and date of last activity. Maybe I can add a third field, date of last presentation in the TOC. Maybe--I'll have to give it some thought.

It's always fascinating to see unanticipated behavior emerge from a complex system.