Event should not appear on specific day if it starts on (at least) previous day, and ends before time set up as "Start of the day".
Let's take an example:
Event A (night shift at work) that starts today at 7pm and ends tomorrow at 3am.
Currently it shows up on both days. Today with times being presented as "7:00 PM - May 16", and tomorrow as "May 15 - 3:00 AM". It is greatly confusing if I want to check calendar quickly for a day off for example. It should be possible to switch to alternative display, causing it to display only on May 15th as "7:00 PM - May 16 3:00 AM".
I would see "Start of the day" time setting as a limit for that option. Let me explain what I mean with another examples:

Event B starting at 11:00 PM on May 15th, ending at 10 AM on May 16th, with "Start of the day" set at 8:00 AM would show up on both days, as it "gets" 2 hours of the day on May 16th. So on May 15th I would see "11:00 PM - May 16 10:00 AM" and on May 16th I would see "May 15 11:00 PM - 10:00 AM".

Event C starting at 10:00PM on May 15th ending on 4:00 AM on May 17th, would appear as:
"10:00 PM - May 17 4:00 AM" on 15th
"May 15 10:00 PM - May 17 4:00 AM" on 16th
Not appearing on May 17th as it ends before "day" starts

Event D starting at 10:00 PM on May 15th ending at 11:00 AM on May 17th:
"10:00 PM - May 17 4:00 AM" on 15th
"May 15 10:00 PM - May 17 4:00 AM" on 16th
"May 15 10:00 PM - 11:00 AM" on 17th.

"May 15 10:00 PM" on month view in widget should (not detail popup in month view) be displayed as "May 15" to save space.