[kronolith] dynamically setting share permissions

[Jason Fleisher]

Is it possible to dynamically add show and read permissions to any given 
share for the guest user? Rather than have new users set permissions for 
guest users on their calendars, I'd like to loop through the available 
shares (Horde_share::listAllShares) and add the read and show 
permissions for the guest user to that share. 
DataTreeObject_share::addUserPermission( null, 6 ) doesn't seem to do it.

The other option is to have the guest user shares default when the new 
shares are created. Where would that be done?

Thanks-

Jason