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

[martin rudalics <rudalics@gmx.at>]

 > 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