> But I wonder if this will break people who use XEmacs in terminal
> mode only?
It's possible (tho I suspect, if so, that it would apply only to XEmacs
*built* without GUI support, rather than merely used in terminal mode).
> It might also just be crufy from ancient support of various
> Emacs/XEmacs versions where testing for features was more problematic?
That's my assumption, yes. And also the fact that I don't really care
about XEmacs compatibility. I didn't throw away XEmacs-specific code
(which I'd do if I were to maintain the package), but I recommend you
let XEmacs users send you patches if/when things break for them.
There's already plenty of work to do getting the code to work well on
recent Emacsen that any backward compatibility should be
a secondary concern.
Stefan