bug#51883: 29.0.50; Command to get accidentally deleted frames back

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: Eli Zaretskii <eliz@gnu.org>,  michael_heerdegen@web.de,  Gregory
>  Heytings <gregory@heytings.org>,  51883@debbugs.gnu.org
> Date: Mon, 24 Jan 2022 20:12:48 +0200
> 
> While copying some code from `clone-frame` to `undelete-frame`,
> I noticed that `clone-frame` doesn't work on non-GTK builds,
> because window-id frame parameters keep frame-specific X-windows,
> so `clone-frame` is broken in emacs-28.
> 
> Eli, is it ok to push the first patch to the release branch?

I don't yet understand the change.  I could understand why window-id
should be removed, but why parent-id, for example?

Martin, any comments on this change?