<?php
// bail if not on the wp-admin Event edit screen
global $current_screen;
if (
! class_exists( 'Tribe__Admin__Helpers' )
|| ! Tribe__Admin__Helpers::instance()->is_post_type_screen( Tribe__Events__Main::POSTTYPE )
|| empty( $current_screen )
|| 'post' !== $current_screen->base // the events post type's add/edit screen
) {
return;
}