bug#38296: Allow Option key to be modifier for non-char key and mouse events

[Alan Third <alan@idiocy.org>]

On Tue, Nov 26, 2019 at 10:36:32PM +0100, Mattias Engdegård wrote:
> 26 nov. 2019 kl. 21.33 skrev Alan Third <alan@idiocy.org>:
> 
> > I had wondered about doing something like this, but not as flexible.
> > Is this the exact interface used by the Mac port? I’m not keen on the
> > word ‘ordinary’, but there’s no use in us doing something different.
> 
> Yes, it's the exact interface, except that the Mac port also allows
> an optional :button property for emulating multi-button mice. I
> didn't bother including that, but nothing prevents adding it later
> on.

I’m happy with that then.

> > +The modifiers themselves can be customised;
> > 
> > I think that should be a colon at the end, not a semi‐colon, although
> > my grasp of semi‐colon use is tenuous at best.
> 
> A @pxref command immediately follows, so the entire sentence would come out as
> 
>   The modifiers themselves can be customised; see Mac / GNUstep Customization.
> 
> Wouldn't the semicolon be more appropriate there? It does not really precede an elaboration, just another main clause.
> I'm no native English speaker, though.

I’m always suspicious of semi-colons because there are two types of
English speakers: those who don’t know how they’re used and therefore
don’t use them, and those who don’t know how they’re used and
therefore use them everywhere. ;)

I’ve had a quick look through the Emacs documentation and I found at
least one other example of using the semi‐colon like this, so I’m
happy leaving it.

> > +The value of each variable is either a symbol, describing the key for
> > +any purpose, or a list on the form
> >                         ^
> >                        of
> 
> I'm torn here. What about 'having' instead?

Having works, but the phrase is ‘of the form’.

    https://en.wikipedia.org/wiki/Of_the_form

I actually just assumed it was a typo. :)

> > +@key{Option} key in macOS is normally used for composing additional
> > 
> > I would remove the word ‘normally’. I think it’s redundant since we’re
> > already talking about ‘standard behaviour’.
> 
> Yes, but the phrase is then conditional on the symbol actually being 'none'.
> Perhaps replacing 'normally' with 'then' would do?

Yes, sounds good.

Oh, and thank you for actually documenting this. It was on my todo
list for the Emacs 27 release.

-- 
Alan Third