Small correction to the patch (for Trusty, maybe it also works in newer releases).
The condition should be "begin < a.end" instead of "begin <= a.end", or else all-day events would also be displayed when the next day is selected.
I also tested events that span multiple days, and it works correctly. The ongoing events for today are correctly displayed.
The calendar, however, only highlights (in bold) the first day of multiple-days events, which is another small bug.
Small correction to the patch (for Trusty, maybe it also works in newer releases).
The condition should be "begin < a.end" instead of "begin <= a.end", or else all-day events would also be displayed when the next day is selected.
I also tested events that span multiple days, and it works correctly. The ongoing events for today are correctly displayed.
The calendar, however, only highlights (in bold) the first day of multiple-days events, which is another small bug.