Re: Supporting stylistic sets

[Nicolas Ouellet-payeur]

> That would disable ligation in complex script shaping, where it is a
> must.

That's why the default mode-line would have a text property on the parts
that are likely to ligate.

e.g. if my mode-line reads like:

-:--- foo.c   All   L1    (C Abbrev)

Then we'd apply this text property on the "-:---" part.

> This slowness is the main disadvantage of our current method of
> handling character compositions.  (It also has numerous advantages.)
> If we want to progressively increase the use of text-shaping engines
> when rendering text, we will need to redesign this part

What do you mean by "this part" specifically? The part where we call
into Lisp for any character in `composition-function-table'? Or the fact
that we do a regex match each time?

> The status quo is NOT that we don't support ligatures.  The support is
> available

Of course. By OOTB (out-of-the-box) I meant reading the GSUB table so we
can apply ligatures *without* requiring manual configuration. i.e.
making the shaping engine do the heavy lifting.

Are we OK with the status quo then, where ligatures have to be manually
configured? In that case, I could send a patch to remove that item from
etc/TODO.