bug#41422: 27.0.91 and 28.0.50; macOS: lower-frame on child frame lowers parent frame

[Aaron Jensen]

This reproduces on master with emacs -Q as well as emacs-27.

emacs -Q

Make sure Emacs is positioned above another app

M-: (make-frame `((parent-frame . ,(window-frame))))

Then, in child frame:

M-: (lower-frame)

This causes the parent frame and child frame to lower below the other
app. I believe, according to the docs, it should do nothing because
there is only one child frame.

Aaron