bp_nouveau_messages_at_on_tinymce_init( $settings,  $editor_id )

function bp_nouveau_messages_at_on_tinymce_init( $settings, $editor_id ) {
	// We only apply the mentions init to the visual post editor in the WP dashboard.
	if ( 'message_content' === $editor_id ) {
		$settings['init_instance_callback'] = 'window.bp.Nouveau.Messages.tinyMCEinit';
	}

	return $settings;
}