inathought

Great script. I’ve updated it to work with navigation with more than two levels deep without losing the absolute parent.

function is_tree($pid)
{
	global $post;

	$ancestors = get_post_ancestors($post->$pid);
	$root = count($ancestors) - 1;
	$parent = $ancestors[$root];

	if(is_page() && (is_page($pid) || $post->post_parent == $pid || in_array($pid, $ancestors)))
	{
		return true;
	}
	else
	{
		return false;
	}
};