[Plugin: All-in-One Event Calendar] FIX: Multi-day events only display once in Month view

I encountered the bug yesterday where a multi-day event will only show on the first day in the Calendar Month view.

After spending an hour understanding how the insides of the plugin works, I found a fix for it:

File: /app/helpers/class-ai1ec-calendar-helper.php
Function: get_events_for_month
Lines: 85-90

Replace

// Itemize events that fall under the current day
foreach( $month_events as $event ) {
	$event_start = $ai1ec_events_helper->gmt_to_local( $event->start );
	if( $event_start >= $start_time && $event_start < $end_time )
		$_events[] = $event;
}

With

// Itemize events that fall under the current day
foreach( $month_events as $event ) {
	$event_start = $ai1ec_events_helper->gmt_to_local( $event->start );
	$event_end = $ai1ec_events_helper->gmt_to_local( $event->end );
	if( $event_end > $start_time && $event_start < $end_time )
		$_events[] = $event;
}

Explanation:

//   ----- BEFORE ----- //
//   IF the Event starts after the start of the day [A]
//   AND the Event starts before the end of the day [B]
//                A                             B
//  |-------------------------|    |----------------------|
if( $event_start >= $start_time && $event_start < $end_time )

//   ----- AFTER ----- //
//   IF the Event starts before the end of the day [B]
//   AND the Event ends after the start of the day [A]
//             A                            B
//  |----------------------|    |----------------------|
if( $event_end > $start_time && $event_start < $end_time )

Hope it helps!

http://wordpress.org/extend/plugins/all-in-one-event-calendar/