Start time field and End time field depend on eventRecord.getAllDay() value. If your event is all day record, it sets allDayField to true state and changes visibility of start/end time fields, so they a hidden (even if allDayField is hidden). Non-allday events always have time fields visible. So I can advice just provide "AllDay" : true to your data. You can also override Sch.widget.EventEditor.toggleAllDayFields to an empty function, if you don't want to see time fields permanently. But this might break EventEditor logic, since time fields won't be available and you cannot change time of non-allday events.