bug#27647: 26.0.50; Line numbers implemented natively disappear momentarily when frame out of focus

[Eli Zaretskii]

> Date: Sun, 15 Oct 2017 11:39:23 +0200
> From: martin rudalics <rudalics@gmx.at>
> CC: rom.skiad@gmail.com, 27647@debbugs.gnu.org, kaushal.modi@gmail.com, 
>  jonaswestlund101@gmail.com, npostavs@users.sourceforge.net
> 
>  > To make line numbers disappear, some code has to trigger redisplay
>  > with display-line-numbers somehow reset to nil.
> 
> Buffer-locally.

Yes.

> I suppose this will become clear as soon as the OP has
> tested your "What if you turn on display-line-numbers globally".

Yes, that's the reason for that request.

> In either case it seems that we do something subtly different when
> processing GTK and native tooltips.

Indeed, the processing is very different (unsurprisingly).

> Since AFAICT the GTK tooltip related code does not change the
> internal (frame-, display-related) state of Emacs I can only think
> of the native tooltip code doing something which prevents the OP's
> behavior from happening.  But I've found nothing supporting such a
> claim in ‘x-show-tip’.

Neither did I.  In fact, the GTK code is much simpler, and I cannot
for a moment figure out how it could have switched buffers behind our
back (if that's what happens in this scenario).