bug#45799: 28.0.50; Faces shrink unreadable on GUI when foreground/background color set in TUI

[Jean Louis <bugs@gnu.support>]

* Eli Zaretskii <eliz@gnu.org> [2021-01-11 23:31]:
> > From: Jean Louis <bugs@gnu.support>
> > Date: Mon, 11 Jan 2021 22:44:08 +0300
> > 
> > When I use `emacsclient -c -nw' for `customize-faces', `default' and
> > unset foreground and background color, the GUI faces shrink to miniscule
> > sizes that I cannot even read any more.
> 
> Don't do that: Customize changes the faces globally, not only for the
> frame where you do it.  It's the wrong tool if you want to customize
> faces on some frames, but not others.  Use set-face-foreground and its
> ilk.

For your and my better understanding:

- I had to unset foreground and background colors, as I wanted to use
  emacsclient -nw in xterm but the current theme was not quite
  readable in console

- to change the theme with customize-themes, I had to unset foreground
  and background color, as otherwise changing theme simply does not
  work. This may be another bug, and I do so for many months as a
  workaround to change the them. Usually I unset the
  foreground/background color, even if under emacs -Q and only then I
  am able to see the changes of the changing themes function
  customize-themes

- but this time I had both GUI and console, unsetting
  foreground/background color in console, made GUI have miniscule
  faces or fonts

Thus my intention is and was not to change the background and
foreground color, rather to unset it so that I can change the theme.

When the GUI practically disappears due to shrinkage of faces, that
still seem a bug, and shrinking faces are to me as user not related to
unsetting of foreground and background colors.