[libwnck] wnckprop: Force usage under X11 only

[Marco Trevisan <marcotrevi src gnome org>]

commit faf6b9d14c0ae47ecef3eb8c32ac818e521966b3
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Fri Nov 23 16:00:53 2018 -0600

    wnckprop: Force usage under X11 only
    
    wnckprop can be used also in Wayland environments to manage XWayland windows,
    but in order to do this, we need to force the x11 backend to be used.

 libwnck/wnckprop.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/libwnck/wnckprop.c b/libwnck/wnckprop.c
index 79b8693..9a0d3ab 100644
--- a/libwnck/wnckprop.c
+++ b/libwnck/wnckprop.c
@@ -1867,6 +1867,8 @@ main (int argc, char **argv)
   bind_textdomain_codeset (GETTEXT_PACKAGE, "UTF-8");
   textdomain (GETTEXT_PACKAGE);
 
+  gdk_set_allowed_backends ("x11");
+
   ctxt = g_option_context_new (NULL);
   g_option_context_set_translation_domain (ctxt, GETTEXT_PACKAGE);