If you select a message (or group of messages) and move them to another
folder, and, while that move is progressing, select another message - when
the move completes, it will select the "next" message if the one where the
move left off with, even if your selection has changed since the move began.

so, say I have messages 1 - 10 and I select 2 thru 5 to move to another
folder. while it's moving messages, select message 7. when the move
completes, it will auto-magically select message 6.

this is especially bad if you are hitting delete for message 7 when it
switches to message 6 (as an example)