function eventorganiser_restrict_events_by_category()
{
    global $typenow;
    $category_tax = get_taxonomy('event-category');
    if ('event' == $typenow && $category_tax && wp_count_terms('event-category') > 0) {
        eo_event_category_dropdown(array('hide_empty' => false, 'show_option_all' => $category_tax->labels->view_all_items));
    }
}
function eventorganiser_restrict_events_by_category()
{
    // only display these taxonomy filters on desired custom post_type listings
    global $typenow, $wp_query;
    if ($typenow == 'event') {
        eo_event_category_dropdown(array('hide_empty' => false, 'show_option_all' => __('View all categories')));
    }
}