Calendar has type mismatche issues where event ids are obtained as strings even when they are numbers, this is (ish) why get_id_index was added to Dataset. When having an event_id in calendar, can't use event_id directly needs to ensure we have valid index and use that index to get "correct (ly typed)" id from dataset. bzr revid: xmo@openerp.com-20130516144904-hbfd5zkl8lic33n8