A function which adds classes to event pages corresponding to the event

event-body-class.php

<?php
/**
 * A function which adds classes to event pages corresponding to the event
 * E.g. adds 'eo-event-cat-[cat slug]' class for each category the event belongs to.
 * Adds 'eo-event-venue-[venue slug]' if the event has a venue
 * Adds time based class: eo-event-future/past/running for future/past/running events
 *
 * @url http://wordpress.org/support/topic/problem-with-highlight-in-menu-change-url-of-events?replies=8#post-3458829
 * Not tested
*/
add_filter( 'body_class', 'my_event_organiser_add_classes_to_event_body');
function my_event_organiser_add_classes_to_event_body($classes){
 
     if( !is_singular( 'event' ) )
          return $classes;

     $event_classes = eo_get_event_classes( get_the_ID() );

     return array_merge( $classes, $event_classes );
}
?>