Version details: 2.3.7
Distribution/Version: Ubuntu 5.10 prerelease

When viewing messages sorted by date, grouped by thread, a new reply to an old
thread goes unnoticed.

The date of a thread should be the date of the most recent message in the thread
so that the most recently active thread appears at the top of the message list
(or bottom, depending on ascending/descending setting).

I wonder if the Group By option under View->Current View->Define Views...->Edit
is supposed to do this, but adding items to the Group By list doesn't have any
obvious effect, irrespective of the setting of the Group by Threads option.