>  > (if (not (display-graphic-p))
>  > ;; Installation of Hyperbole requires a non-dumb terminal
>  > ;; instance of Emacs, i.e. under a window system.

Why do you need that?  IOW, what doesn't work on a TTY frame?  I don't
expect to see any real problems, since in a modern Emacs version most
features "just work" on TTY frames.  Colors, menus, dialogs, mouse,
everything.  There could be some old code you have that fails because
it uses low-level or obsolescent APIs, but that's about all I'd
expect.

So please tell why you needed to enforce display-graphic-p.