bug#36879: 26.2; OSC 52 paste in term/xterm.el not working

[Daniel Eklöf]

> - I did test the code with the xterm that comes with Debian.
>   I definitely remember making it work it in one direction 
>   (paste or
>   yank, can't remember), not sure if I did get it to work in 
>   both
>   directions at the time.

set-selection has always worked, at least for me. That one is also 
enabled by default in xterm.el (when an xterm supporting it is 
detected, I assume).

> - The feature is fundamentally dodgy from a security 
> perspective.

I'm probably missing something obvious, but how is talking to 
xclip more secure than talking to the terminal emulator? Or is the 
"security perspective" somewhere else?

> So I'm not sure it's worth the trouble supporting this, really:
> In many/most cases `xclip-mode` can be used instead, and is much
> more straightforward.

Except that xclip assumes x11. Would it not make sense to support 
a window protocol agnostic method? By supporting OSC 52, you 
support whatever clipboard mechanism the terminal emulator 
supports.

Perhaps one could use the heavy weight solution (change quit char) 
when 'screen' is detected, but simply use ST in the non-screen 
case?

(before I tried this, OSC 52, I was using 
https://github.com/bugaevc/wl-clipboard with my own Emacs 
"bindings" - yes, I'm on Wayland)