Version:           2.0.89 (using Devel) 
OS:                Linux

Sometimes, when reading emails using the Next Unread Message (Plus) and Next Unread Folder (Ctrl+Plus), after a new folder is selected, the selection is stuck and won't unselect the first item that was selected with just the Next Unread Message command.

The selection clears with the Next Message (Right) or Previous Message (Left).

This has effects on the Forward, Delete/Trash, and Move/Copy commands, since they operate on multiple mails.

Reproducible: Sometimes

Steps to Reproduce:
1. Ensure you have a folder with more than one unread email
2. Select a folder that is sorted before it in the message list
3. Press Ctrl+Plus
   The folder with the unread email is selected
   The first unread email is selected (most of the time)
4. Press Plus

Actual Results:  
Both emails are selected. Pressing Plus again has two behaviours:
 a) the original email is kept selected, the one being viewed is unselected and a newly unread email is selected (selection count remains at 2)
 b) the original email, the one being viewed and a newly unread email are selected (the selection count increases to 3)

Expected Results:  
The original email is unselected and the new email is selected. The selection count is 1.

OS: Linux (i686) release 2.6.36.2-server-1mnb
Compiler: gcc

This does not happen all the time.

This was observed also in KMail 1.x, with variant (a) in behaviour. I have never observed more than 2 emails selected when doing this in KMail 1.x. However, this issue happened more frequently in KMail 1.x.