bug#50112: 28.0.50; ediff help frame does not display text

[martin rudalics]

> I built emacs this morning from the git master branch.
> The latest commit was 9b31ad36094666da6b3281025adc163829d89de8 with
> a date stamp of Wed Aug 18 20:02:39 2021 +0300.
> I am running the macos GUI version.
> First I run /Applications/Emacs/Contents/MacOS/Emacs -Q
> then I load two files and run 'ediff-buffers' to compare them.
> ediff works just fine except that the frame with the help message
> is an empty frame. The '?' command changes the frame size but the
> text never renders.

Assuming that in this situation you have two frames - the main frame and
the help frame: What does evaluating the form

(let ((buffer (window-buffer (frame-root-window (next-frame))))
      (foo (get-buffer-create "*foo*")))
  (with-current-buffer foo
    (insert
     (buffer-name buffer)
     "\n"
     (with-current-buffer buffer
       (buffer-substring 1 (point-max))))))

in the main frame via M-: put into buffer *foo*?

martin