Indrajeet

I think I have fixed this here.  Basically, the bug totally breaks the
behavior with -nw but only partially breaks the gui behavior.  In the
latter case, parts of the window structure are corrupted but apparently
these do not substantially inhibit working with Emacs here.  It's not
excluded though, that the NS port fails in the gui case as well.

I attach two fixes for this:

- window.c.diff is the one I intend to install on Emacs 28 soon.

- window-27.diff is one you can install for Emacs 27 provided you are
   able to build Emacs on your system.  It includes the window.el patch
   which is already on Emacs 28.  If you can't build Emacs yourself, I'm
   afraid you have to wait for the new release.

Good luck and many thanks for the forensics, martin