On Fri, Jun 07, 2019 at 03:45:29PM +0200, Óscar Fuentes wrote:

[...]

> One thing that I'll like to know is why the hard restriction about
> C-[/C-i exists at all.

As we've found out, it's not a hard restriction. Just a strong
suggestion.

I think the problem is one of "frame of reference". There's a
(understandable) strong desire to have Emacs behave (as far as
possible) similarly on different display devices. Therefore it
makes sense to unify those things in the GUI that are unified
(by the display device) on a TTY. So you can have the same
keybindings for both.

Imagine for a moment someone binding ESC to some function (or,
since ESC is already taken, let's say DLE, which on a TTY is
equivalent to CTRL-P, hexadecimal 10). Let's assume that user
states the binding in her ~/.emacs/init.el. She would have all
right to expect that things work the same for a TTY and say, X.

Therefore it makes sense to (by default!) unify them under X,
although in that context, you could differentiate them.

To me, architecturally, the right thing to do is to introduce
another mapping layer which does that unification -- before
the regular keymaps get a chance to act. As far as I understood,
this is input-decode-map.

This being Emacs, you are of course allowed to tinker with
that.

Seen from here, that hoop makes sense. It will stop making sense
once the TTY backends are gone (this may take some time: even
the newfangled Raspberry Pi come with a serial interface :-)

Cheers
-- tomás