[Dovecot] After upgrade from 1.0 to 1.1.1 my "hidden" private namespaces suddenly aren't hidden anymore...

Just upgraded my home mail server from version 1.0 to 1.1.1 and now I noticed that Thunderbird has started showing the 'hidden' namespaces (albeit "greyed") for that server (see the attached JPG image)...

What can I change to really make them hidden again?

The only thing I changed in my dovecot.conf file from 1.0 to 1.1.1 was to add the following two lines:

 mail_nfs_storage = yes
 mail_nfs_index = yes

• Peter