Balsa 2.2.3: can't change sort order (from/subject/date) with threading enabled

[Miquel van Smoorenburg <miquels cistron nl>]

I just noticed that with balsa 2.2.3, if I click on any of the
From/Subject/Date/etc headers in the message listbox, the
sorting order doesn't change as it did before.

Turning off threading (View -> Flat Index) makes it work, and
in fact, those settings stick after I reenable threading.
So the workaround is to temporarily disable threading
when changing the sort order.

Mike.