Re: macOS child frame lower behavior

[martin rudalics]

> I recently filed this: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=41422
>
> I was curious if this behavior is expected and/or known. It doesn't
> fit the docs, but it could be a limitation of macOS. I know child
> frames have differences from OS to OS.

It is not the expected behavior and AFAICT it behaves on GNU/Linux and
Windows as described in our docs.

Note that, for example, the description of the XLib manual says about
XLowerWindow (which we call from x_lower_frame)

  The XLowerWindow() function lowers the specified window to the bottom of
  the stack so that it does not obscure any sibling windows.

and that of gdk_window_lower (which we do not call currently but would
have to call in a "pure" GTK build for non-X systems) says

  Lowers window to the bottom of the Z-order (stacking order), so that
  other windows with the same parent window appear above window.

I cited these because I expect the corresponding method called by
ns_lower_frame (orderBack) do the same.  According to its doc

  Moves the window to the back of its level in the screen list, without
  changing either the key window or the main window.

it should but that depends on what "level on the screen list" precisely
means.

If it doesn't do the same, we likely have a bug but I cannot check that
here.  Maybe you can try to find out what ns_lower_frame does on your
system.  And maybe you can tell us whether 'ns-frame-restack' behaves as
documented too.

Thanks, martin