Thunderbird + Kerberos 5 + Cyrus SASL-and-IMAP?

[Jeff Blaine]

I have a healthy MIT Kerberos 1.5.2 realm and Cyrus IMAP 2.2.12
server configured (SASL 2.1.22).

I can't get Thunderbird (latest 1.5 official release) to perform
GSSAPI authentication against the Cyrus IMAP server.

I have valid Kerberos 5 credentials (for user jblaine) via Kerberos
for Windows 3.1.  I have restarted Thunderbird.

Anyone know how to do this?  This is supposed to work if I am
not mistaken.

Thunderbird states the server does not support secure authentication
(which is BS).

====================================================================

imtest authenticates (as jblaine) via GSSAPI fine!

C: A01 AUTHENTICATE GSSAPI YIICBblahblahblah
S: + YIGWBgkqhkblahblah
...
S: A01 OK Success (privacy protection)
Authenticated.
Security strength factor: 56

...

Feb  8 16:36:44 noodle.foo.com imap[26514]: [ID 529592 local6.notice] 
login: noodle.foo.com [192.168.168.100] jblaine GSSAPI User logged in

====================================================================

/etc/imapd.conf reads as follows:

configdirectory:        /var/imap
defaultpartition:       default
partition-default:      /var/spool/imap
imap_admins:            root cyrus
sieveusehomedir:        false
autocreatequota:        200000
duplicate_db:           skiplist
allowplaintext:         false
force_sasl_mech:        GSSAPI
sasl_log_level:         4