Comment 3 for bug 768962

I used this in a custoim module indeed, but this doesn't means it's not a bug. Moreover, date_stop is documentated here :

http://doc.openerp.com/v6.0/developer/2_6_views_events/views/calendar_view.html

Just define a simple model with 2 datestime dields (begin, end) and test it.