[Dovecot] Access to the root of a shared mailbox

[RIOTTEAU Gwénaël]

I have an issue with shares mailboxes

Example : I have 2 users A and B.
  A must have an access to all mail of B
  So i create a public namespace

namespace public {
   separator = /
   prefix = Public/
   location = maildir:/home/users/B/Maildir
}

It's OK for the subfolders, but not for the root (B's inbox, the most  
important !)

it's seems to be like  
http://www.dovecot.org/list/dovecot/2007-October/025965.html
it's the only feature that prevents me to migrate from Courier-IMAP !