Some more info:

After adding a group to a "nag" share, nag dies on startup.

1. Nag_Form_Task->__construct() 
/datastore/share/pear/www/horde/nag/task.php:81
2. Horde_Group_Intranator->listUsers() 
/datastore/share/pear/www/horde/nag/lib/Form/Task.php:105

Complete back trace:
Horde_Exception_NotFound Object
(
     [details] =>
     [logged] => 1
     [_logLevel:protected] => 0
     [message:protected] => Not Found
     [string:Exception:private] =>
     [code:protected] => 0
     [file:protected] => /datastore/share/pear/Horde/Group/Intranator.php
     [line:protected] => 126
     [trace:Exception:private] => Array
         (
             [0] => Array
                 (
                     [file] => 
/datastore/share/pear/www/horde/nag/lib/Form/Task.php
                     [line] => 105
                     [function] => listUsers
                     [class] => Horde_Group_Intranator
                     [type] => ->
                     [args] => Array
                         (
                             [0] => Neue Gruppe
                         )

                 )

             [1] => Array
                 (
                     [file] => /datastore/share/pear/www/horde/nag/task.php
                     [line] => 81
                     [function] => __construct
                     [class] => Nag_Form_Task
                     [type] => ->
                     [args] => Array
                         (
                             [0] => Horde_Variables Object
                                 (
                                     [_expected:protected] => Array
                                         (
                                         )

                                     [_sanitized:protected] =>
                                     [_vars:protected] => Array
                                         (
                                             [Horde] => 
2bqso35eigbloih72jpbqj3ue5
                                             [actionID] => add_task
                                             [tasklist_id] => 
Vny7s2HkBf6DVHwF7B5eMw2
                                         )

                                 )

                             [1] => New Task
                         )

                 )

         )

     [previous:Exception:private] =>
)


-> One can see that it tries to call 
"Horde_Group_Intranator->listUsers()" with the group name instead of 
the group id. I've digged a bit around the code and can see that the 
Kolab $share returns the group name instead of a group id.

For now I've traced it to Horde/Share/Object.php::listGroups() calling 
$perm->getGroupPermissions(). This somewhere ends up in 
Horde/Perms/Permission/Kolab/Acl/Group.php.  Adding a debug trace to 
::toHorde() shows "$this->_id" is the group name.

-> The custom "Intranator" group driver uses an integer id as group id 
while the Kolab backend expects the "group name" as id. I'll fix my 
custom group driver since the Kolab backend does not have any "id" 
information available from the "group:NAME" acls on the IMAP server.

Hi,

I tried to share a Kolab folder with a group.

When I add the group perm to a Kolab share, the newly added perm is 
added on the IMAP server. This new perm completely vanishes from the UI.

When I re-enter the perms dialog, it also doesn't load the group 
permission properly.
-> It's not displayed.

Thomas