When you go to the Messaging -> Calendar view, select the monthly view, click the calendar and then select "Edit event", the form that opens has the "All day" checkbox checked by default. Is it possible to override this so that the checkbox is not checked?
Apparently the default value is somehow controlled by the FullCalendar JS library, since neither using the _defaults dictionary or overriding the action's context with { 'default_allday': False } seems to work.
Thanks!