Location: In
functions_admin.php method delete_topics. I think its around line 682 where we could fire the event.Parameters: at least the variable
$topic_ids (holding the ids of topic(s) that are deleted).Explanation: Deleting a topic requires extensions to delete data that is related to the topic.
Ticket: https://tracker.phpbb.com/browse/PHPBB3-13658
PR: https://github.com/phpbb/phpbb/pull/3452