[Evolution] The Unread count bug revisited

[Patrick O'Callaghan <pocallaghan gmail com>]

Several people (including me) have complained that on occasion Evo shows
the wrong count of Unread messages in a folder, e.g. it shows an Unread
count of 1 when all the messages have been read.

I've recently been experimenting with this, and now have a reliable way
of 1) creating the problem, and 2) fixing it. Note that there may be
more than one bug here (BZ has several reports and it's not clear if
they're all talking about the same thing), so this may not work for you.
Nevertheless, I think it's interesting. The report is at:

https://bugzilla.gnome.org/show_bug.cgi?id=577542#c13

Briefly, you can create the problem by dragging a deleted but Unread
message from an IMAP folder to a local one. You can fix it by marking
one or more Read messages as Unread while watching the Unread count. As
long as the count is inconsistent, marking messages as unread *will not
increment it*. When the count becomes equal to the number of marked
messages, it returns to consistency. If you then mark the messages as
read, the count will decrement and remain consistent (until the next
time of course :-)

poc