I love the new Smart Folders, exactly what I needed to finally let
Windows Live Mail go. However, WLM could figure out how to
automatically go to the next message in the Smart Folder list when I
delete the current message. Thunderbird appears to have a problem with
this task.

When I delete the current message in Thunderbird, the message is
deleted in the message list of the Smart Folder Inbox, but I still see
the message in the tab. Thunderbird doesn't go to the next message?
The nav_crosses_folders option has no effect on Smart Folder
navigation. Any clues?