bug#25474: 26.0.50; Buffer content invisible

[Daniel Colascione]

On Fri, Jan 20 2017, Eli Zaretskii wrote:
>> From: "Ivor Durham" <ivor.durham@ivor.cc>
>> Cc: <25474@debbugs.gnu.org>
>> Date: Thu, 19 Jan 2017 09:05:19 -0800
>> 
>> Disabling XDBE fixes the problem. Thank you.
>
> Thanks for testing.
>
> Daniel, could you please look into this?  If this is something
> specific to this particular X server, and it cannot be fixed/worked
> around in Emacs sources, perhaps we need a run-time option to disable
> double-buffering for a certain display?

I'll take a look. It may be worthwhile to just ditch XDBE and use a
pixmap instead --- that'd complicate the code in Emacs and potentially
(but not necessarily) reduce performance, but it would at least trigger
fewer X server bugs.

In the meantime, you can disable double buffering using the
inhibit-double-buffering frame parameter, e.g.,

  (modify-frame-parameters nil '((inhibit-double-buffering . nil)))