bug#32334: Window resize fails in remote X11

[Robert Pluim <rpluim@gmail.com>]

Robert Pluim <rpluim@gmail.com> writes:

> Eli Zaretskii <eliz@gnu.org> writes:

>> I'm not even sure that's a bug in the X server.  It could be a bug in
>> our code, for all I know.  If we arrive at the conclusion that it's a
>> bug in the server, that would be a very good progress, IMO.
>
> Iʼm going to have to agree with you: the changes to support
> double-buffering in emacs are far more extensive than I initially
> thought, so bugs are definitely possible.

I tested this quickly last night with VcXsrv, and itʼs utterly broken
with emacs-26 built for GTK when using double buffering: the entire
text area of the initial frame never gets updated. With lucid itʼs
slightly better in that half the frame gets refreshed. That does
suggest that the bug is in emacs (especially since VcXsrv is
essentially xorg recompiled for Windows).

Initial debugging showed that the appropriated XDBE calls are being
made, so perhaps the initial setup of the frame is at fault. More
debugging this weekend, I hope.

Robert