> I’ve had a dig around and it looks as though emacsclient is able to
> open a new GUI frame, so it’s not quite as dire as I’d previously
> thought.

Oh, neat. I hadn't tested that, so that's good to know.

> There are two problems, though.

> * Application Menu

> When the last NS frame is deleted the menus aren’t updated, so I think
> they’ll be the menus as defined for the last frame. They should
> probably be cut right back to just the ‘Emacs’ menu, and perhaps
> ‘help’.

Won't those menus just get updated once a new frame is created? I'm not
exactly sure what the implications of this are.

> (NOTE: The menus are a bit of a mess, Nick Helm and I have been
> discussing them in bug#31371.)

I read your discussion at bug#31371 ( here's link for others' reference:
https://lists.gnu.org/archive/html/bug-gnu-emacs/2018-05/msg00149.html ).
Strangely, this bug doesn't occur at all on the Emacs Mac Port. The Help
menu search actually works fantastically on the Mac Port. It can show
info nodes, menu items, and it actually works when you click on
them. Here's a screenshot: