When a comment is added to an existing thread in a pull-request, that thread stays at the same position in the list of activity. New comments on old threads can be buried so deep that they can’t even be searched for without first scrolling to the bottom to force them to load. I’d prefer if threads with new comments always percolated to the top of the list so the most relevant information is always at hand. I would consider it a plus if it were configurable.