[mms] Fix dragging a mailbox to the base level in dynamic view.

Additional improvement: Like the other mailboxes, now allows a drag to
anywhere in the containing div rather than onto the interior text only
[mms] Fix fatal error in signup confirmation script.
Fix another missing CHANGES entry

This might be something we need to look for at H6 also, because I've
seen a bunch of changes made in FW_5_2 lately that haven't been forward
ported into git master so they are getting lost