Description:
   When reading messages, one often wants to
delete messages and/or travel to the next unread
message.  This works fine in normal folders. 
However in threaded folders, 'next unread' and
'delete' go to unpredictable messages. 
Specifically, they seem to be travelling in the
order of the date, even though that is *not* the
order of the thread.  I have had the following happen:

N  msg 0
   msg 1
N  \msg 2
   msg 3
N  msg 4

    I read msg 0.  I then pres 'n' (goto next
unread message).  This jumps to msg 4, not to msg
2.  That is counterintuitive and completely
violates the principle of least surprise.  This
also seems to happen sometimes with '^d' (Delete).
Hmm.  I wonder if this is the result of 'Hide
deleted messages' confusing ETree.  I'll look at
that, but certainly the 'next unread' issue
wouldn't be that.

Platform:
    Debian Sid Latest
    Evolution package 1.0.3-3