On Wed, Jul 01, 2015 at 03:07:12AM -0700, Ilya Zakharevich wrote:
> On Wed, Mar 04, 2015 at 08:01:01PM +0200, Eli Zaretskii wrote:

> > I suggest, indeed, to clean up the code so we could commit it to the
> > master branch.  That way, it will get wider testing, and we can fix

> I had no time to work on the code itself, but
>   • I fixed the formatting,
>   • I pumped up the docs,
>   • I put in the suggested eassert().

The variant I sent was too primitive — it was not covering a (common?)
usage case when (with AltGr-layouts) leftCtrl+rightCtrl was behaving
differently than pressing AltGr:
   • leftCtrl+rightCtrl would trigger C-M-key;
   • altGr would enter the character payload.

This update

  (0) fixes two formatting-style omissions;

  (A) adds A LOAD of new comments;
  (B) treats such important cases (as above) separately;

  (z) Marks a piece of old code which does not make any sense.
        (see the last chunk in the relative patch)

Notes:

  • In (B), there are some decisions to make.  I encapsulate these
    decisions into two strings.  For best result, these strings should
    be user-customizable.  However, currently they are just put into
    C #defines.

    When I sit on this more, and if these customizations turn out to
    be useful, one can make them into Lisp variables.

  • There is a bug in the (old) Emacs code which prevents some cases
    treated in (B) from being really useful.  I did not fix it yet.

    To see the bug:
      ∘ switch to layout with AltGr;
      ∘ assume that AltGr-s produces ß (as with US International);
      ∘ pressing AltGr-rightControl-s produces Meta-ß;
      ∘ pressing rightControl-AltGr-s produces C-M-s.
    (I do not think this effect is intentional.)

  • And, BTW, is it documented anywhere that
    leftControl-rightControl-key produces C-M-key?

I include two patches:
  □   absolute (ignore the previous patches)
  □   relative (with whitespace ignored) — for reading.

Enjoy,
Ilya