Eli Zaretskii <eliz@gnu.org> writes:

>   Not all text terminals have a way of generating non-@acronym{ASCII}
>   control characters, but you can generate them straightforwardly
>   using X and other window systems.

Thanks, I went with this variation:

    Not all text terminals can generate non-@acronym{ASCII} control
    characters, but it is straightforward to generate them using X and
    other window systems.

> I'd prefer to keep the reference to X, something like
>
>   This distinction is possible only when you use a graphical display,
>   such as a GUI display on X.

Fixed.

>> -;; Many people are used to typing C-/ on X terminals and getting C-_.
>> +;; Many people are used to typing C-/ on graphical displays and getting C-_.
>
> In code comments, I'd prefer to use "GUI frames" instead.  it's
> shorter and more accurate, IMO.

Fixed in both cases.  Updated patch attached.