I like the way multi-day events are displayed on the monthly calendar. However I notice that they only show up on the daily calendar on the first day of the event. So the day view can say "There are no events this day" when in reality there is an event which however started on an earlier day.
Finding the multi-day events that need to be shown on a particular day will require some SQL something like "WHERE timestart < dayend AND timestart + timeduration > dayend" where dayend denotes time for the end of the day we are interested in.