bug#1785: bug#1547: face-font-rescale-alist has no effect

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Andrew Hyatt <ahyatt@gmail.com> writes:
> I'm looking at this for Emacs 25, just to see if it can reproduce.  I
> believe this is still the case.  Here's how I attempted to reproduce it
> (keep in mind I don't have any particular knowledge of this
> functionality).
>
> 1) Start emacs with "emacs -Q" in a window (X-windows, or other system
> capable of handling different fonts)
> 2) Eval, in the scratch buffer, (add-to-list 'face-font-rescale-alist
> (cons (font-at 1) 4.0)).

I think that's not right format for face-font-rescale-alist, the car
should be a string, not a font object.  Doing

   (add-to-list 'face-font-rescale-alist '(".*" . 4.0))

and tnen opening a new frame gives enlarged text in the new frame, and
causes only buffer name in the modeline the original frame to be
enlarged.  Also it looks like the buffer name in the modeline of the new
frame is enlarged twice.  So it mostly works, but there is some
difficulty with the existing faces used in the current frame.

Doing

    emacs -Q --eval "(add-to-list 'face-font-rescale-alist '(\".*\" . 4.0))"

does give enlarged text in the initial frame.