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

[Eli Zaretskii]

> From: Philipp Stephani <p.stephani2@gmail.com>
> Date: Sat, 26 Mar 2016 17:31:46 +0000
> Cc: 23009-done@debbugs.gnu.org
> 
> We still might consider solving the flicker problem for "no-conversion". 
> Honestly I don't understand the
> behavior of the meta mode at all: it seems that for the purpose of read-char 
> the meta-mode is completely
> ignored? If so, would it make sense to use 
> set-keyboard-coding-system-internal, which doesn't appear to set
> the meta-mode?

Hmm... what does current-input-mode return on HTerm in "emacs -Q"?  I
expect to see a non-nil, non-t value in the 3rd element of its return
value.  If that's so, then testing that value for identity with the
one we want to pass to set-input-meta-mode, and avoiding the latter
call if the mode is already what we want, might avoid the flickering.

Can you see if this is doable?