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

[Eli Zaretskii]

> From: Michael Heerdegen <michael_heerdegen@web.de>
> Cc: gregory@heytings.org,  51883@debbugs.gnu.org,  juri@linkov.net
> Date: Sat, 27 Nov 2021 15:08:34 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > It is maybe better to ignore an argument of zero, i.e. behave as if
> > there was no argument.
> 
> If we do that (and I don't object) - what should negative arguments do?
> Should -N be equivalent to +N?

Either that or ignored.