bp_forums_highlight_forums_new_parent_menu( $parent_file )

function bp_forums_highlight_forums_new_parent_menu( $parent_file ) {
	global $pagenow;

	$post_type = isset( $_GET['post_type'] )? $_GET['post_type'] : '';
	$forums_post_types = [ bbp_get_forum_post_type(), bbp_get_topic_post_type(), bbp_get_reply_post_type() ];

	if ( $pagenow && 'post-new.php' == $pagenow && in_array( $post_type, $forums_post_types ) ) {
		return 'bp-forums';
	}

	return $parent_file;
}