1. Add a (new version!) Calendar portlet to your page.
2. Create a new event.
3. Click on Edit Details.
4. Fill in the Title.
5. Set the Start date to 04:05 PM.
6. Click on Save.
7. Check the Start date. It has changed to 04:30 PM.
1. Create an event to today 01:45 PM - 03:05 PM.
2. Check it in the table. It's ok.
3. Try to modify. Click on Edit Details, and check the start and end time: 02:00 PM - 03:30 PM.
4. I attached a screenshot.