bug#12279: 24.2.50; x-window-property always returns nil

[Chong Yidong <cyd@gnu.org>]

Tassilo Horn <tsdh@gnu.org> writes:

> Running GNU/Linux with Xorg, since some time I cannot get X window
> properties anymore, that is, using emacs -Q (3 days old bzr checkout),
> all of these return nil:
>
>   (x-window-property "WM_HINTS" nil "WM_HINTS" nil nil t)
>   (x-window-property "WM_PROTOCOLS")
>   (x-window-property "WM_NAME")
>
> I used xprop to get all X properies of the emacs frame itself, and I
> can't get any of them using `x-window-property'.
>
> In GNU Emacs 24.2.50.1 (x86_64-pc-linux-gnu, GTK+ Version 3.4.4)
>  of 2012-08-23 on thinkpad

Can't really reproduce.  With latest trunk, also with a GTK 3 build
(x86_64-unknown-linux-gnu, GTK+ Version 3.4.2), I get

M-: (x-window-property "WM_HINTS" nil "WM_HINTS" nil nil t)
  ==> [2 0 1 0 0 0 0 0 0]

I do get nil when looking up WM_PROTOCOLS and WM_NAME, but that is the
case on 24.1 as well.  On a Emacs 23.4 build with X toolkit, looking up
WM_PROTOCOLS gives "" and looking up WM_NAME gives nil.