bug#23009: 25.0.92; xterm-mouse-mode should not assume UTF-8 coordinates

[Eli Zaretskii]

> From: Philipp Stephani <p.stephani2@gmail.com>
> Date: Mon, 14 Mar 2016 13:56:41 +0100
> 
> I'd suggest the following (and will happily provide patches if
> accepted):
> 
> - Don't enable UTF-8 coordinates at all.  It is too hard to figure out
>   whether they are enabled.  Rather, err on the safe side and only use
>   single-byte coordinates.  (The superior SGR mode, which doesn't suffer
>   from this problem, should remain enabled.)

How about providing a user option, off by default, to enable that?  A
user who knows that this works on her machine will then be able to use
the feature.

> - In `xterm-mouse--read-number-from-terminal', specify a very short
>   timeout.  The terminal will always write the entire escape sequence as
>   a unit, so waiting only increases the chance to accidentially read
>   unrelated events.

Won't this break when working on a remote machine via a slow link?

> - As an optimization, provide a `read-byte' function written in C that
>   reads a single byte without taking the current terminal encoding into
>   account.

You should be able to achieve the same effect by binding
keyboard-coding-system to no-conversion, no?