To get access to the folder handling you would do the following:
require_once 'Horde/Kolab/Storage.php';
$folder = Horde_Kolab_Storage::getFolder('INBOX/Calendar');
or (in case you are dealing with share identifications):
require_once 'Horde/Kolab/Storage.php';
$folder = Horde_Kolab_Storage::getShare(Auth::getAuth(), 'event');
To access data in a share (or folder) you need to retrieve the
corresponding data object:
require_once 'Horde/Kolab/Storage.php';
$folder = Horde_Kolab_Storage::getShareData(Auth::getAuth(), 'event');
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