Fix the Group Calendar Webpart for All Day events
The display of full day events added in a group calendar is shifted by one less day in the group calendar webpart. Adding the same event from 00:00:00 to 23:59:59 displays it correctly.
Paul Hendrix commented
This is actually a bit more insidious. When creating a calendar event, if one selects "all day", the start time and end time are set to "12:00 AM". Consider this event:
Start time: Mon 2/11/2019 12:00 AM
End time: Mon 2/12/2019 12:00 AM
This should be a 24 hour event. That is literally 24 hours between the start and end times. Instead, this is stored as a 48 hour event. The UI is actually setting a "First Date" and "Last Date" of the all day event, not a "Start Time" and "End Time".
Just change the wording and remove the time selectors instead of graying out the and locking the time selectors when the "All day event" checkbox is ticked.
The original comment above is the most glaring symptom of this. In my above example, the calendar event itself, when opened, will show an End time of "2/11/2019 12:00 AM". If you mouse over the event in your calendar, however, it will show you "2/12/2019 12:00 AM". This display bug is obviously wrong.
n != n+1
That said, if the all day event creation dialog UI, which is the same as the event edit/view UI, reflected the underlying functionality, there would be no problem.