bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 20 Dec 2014 18:51:56 +0100
> From: martin rudalics <rudalics@gmx.at>
> CC: holtzermann17@gmail.com, 19194@debbugs.gnu.org
> 
>  >> Probably to know how many characters fit into a line.  With a
>  >> proportional font.
>  >
>  > But for a proportional font, that question has no meaningful answer.
>  > Using the maximum width could yield a result that it a gross
>  > underestimation.  I fail to see how this could be more useful than
>  > using the average width.
> 
> Are we sure that all numbers fit into the average width.  If not, we can
> get problems with line numbers.

Like I said: you will get a wrong answer either way.  I think this is
simply the wrong way to do it.  I cannot suggest a better way without
knowing more about the particular application.

> BTW you probably might want to close bugs 1255, 8379 and 10960 now ;-)

So can you ;-)

>  >> He wants the width of a default font "M" (where the default fount could
>  >> be proportional) filtered by the frame it appears on and the remapping
>  >> specified for the buffer the character appears in.
>  >
>  > Once you get the font used by a face on that frame and buffer, the
>  > font parameters are fixed.
> 
> I lost you here.  Does that mean that with proportional fonts an "M" and
> an "I" have different fonts?

I'm saying that specifying the font by a face on a frame makes any
"filtering" redundant.