Please align starttime and endtime of an all day event to start and end of work day configured in users preferences
All day events start at 4:00 and end at 20:00. Some people would expect them to start at 0:00 and end at 23:59. They start at 4:00 am because of problems with different timezones. The 4 houres are only relevant in the USA and do not apply to the rest ...