bug#64270: 30.0.50; Font update for no toolkit menu

[Po Lu]

>> >> For my usage, I imagine that yes the menu font would change when I
>> >> change the frame's default face.  But this because my menu face is
>> >> already derived from the default face.
>> >> 
>> >> For the general usage, my idea (and what I start doing in my patch, see
>> >> my first message) is to query the MENU_FACE_ID.  So the font into the
>> >> menus would change if the user modify its menu face.
>> >
>> > This is a misunderstanding: I didn't ask what would be the trigger to
>> > change the font.  I asked how would Emacs know _which_ font to choose
>> > for the menus?
>> 
>> I also am not sure I understand.  I don't think that Emacs has to choose
>> a font here.  It would use the font used for the menu face.  What am I
>> missing?

It's unlikely that the font used for the menu face can actually be used
by the XMenu library, since Emacs is in no way limited to utilizing core
X fonts.

I seriously suggest not touching the oldXMenu library and working on
something else.

Thanks.