[Dovecot] LAYOUT=fs still uses 'dot' prefixes for folders

[PGNet Dev]

running latest dovecot HEAD, per,

        http://wiki.dovecot.org/MailLocation/Maildir

i've set LAYOUT=fs,

        dovecot -n| grep -i layout
                mail_location: maildir:/data/mail:LAYOUT=fs

and expect,

        maildirs to actually use physical directories, such as:
            * Maildir/folder/
            * Maildir/folder/subfolder/

but, autocre...@login creates folders using "dot" prefixes, e.g.,

        cd /data/mail/Domains/my.domain.com/Accounts/test_account
        ls -1d .*
                ./
                ../
                .Drafts/
                .Spam/
                .Templates/
                .Trash/

&, login via TBird, creating a folder "test", also creates

        .test/

a bug, or a misconfiguration?