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> [2021-01-12 20:21]:
> > Date: Tue, 12 Jan 2021 19:51:55 +0300
> > From: Jean Louis <bugs@gnu.support>
> > Cc: 45799@debbugs.gnu.org
> > 
> > When I however, entered from xterm, from console mode with
> > emacsclient -nw than after M-x customize-faces default I can see that
> > height is 1 point. And it is set to 1
> > 
> >    [X] Height: Value Menu Height in 1/10 pt: 1                                  
> > 
> > that is what I see if I enter customize-faces from console by using
> > server.
> > 
> >    [X] Height: Value Menu Height in 1/10 pt: 113
> > 
> > Is that normal behavior according to you?
> 
> Yes.  Everything is 1 pixel on a TTY frame.  That's why it's a bad
> idea to customize faces on a TTY frame using "M-x customize-face".

Yes, and no. I use GUI mostly but there are ways why I need emacs on
console, and often themes make the console less readable or contrast
is not good enough. It may be bad idea, but I do not know what better
or else to do to customize console temporarily.

> > It does not sound logical that Height on console should be displayed
> > as 1 as that does not relate to console height
> 
> Emacs has no way of knowing the size of font on text-mode frames, so
> it counts it as 1.  That's the lowest granularity of text size on TTY
> frames, as far as Emacs is concerned, as it cannot reference partial
> character width or height in text mode.  The height of each text line
> is 1 and the width of every character is 1 (with the exception of
> double-width characters, whose width is 2).

OK I understand. Just it is not visible to user. I was not thinking of
height, I just wanted to have some better contrast and missed to see
that height on console is 1.

Still there is problem. You basically say "it is bad idea" advising me
and users to rather avoid the issue on hand.

The issue is that users are allowed to customize faces on console and
that such customization does affect GUI in the same time.

As if Emacs pulls some default for console such as 1, then it should
not affect GUI, but console only.

Or other solution would be to split settings and tell user that
specific customization of face height is for GUI, and other line is
for TUI, something like that.

So if the font on console is 1 then customization of the default face
in console should not affect the GUI. Can we agree on that?