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

[Alan Third]

On Wed, May 20, 2020 at 09:02:00AM -0700, Aaron Jensen wrote:
> 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.

Commit ad2567fb1efced752352096f345c69f88e1ff405 pushed to master,
which should fix this.

I'm sure this worked when I wrote the NS child window code, but I
can't find any indication that the API changed. Anyway, the new code
works as far as I can see.

-- 
Alan Third