[nautilus] preview: Don't assume X

[Cosimo Cecchi <cosimoc src gnome org>]

commit 5305ef253f59f99acb64e4bd5c56bfa6b1a3a76d
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Nov 12 14:47:25 2015 -0500

    preview: Don't assume X
    
    We need to check at runtime if we are actually running under X,
    before calling gdk_x11 API.
    
    http://bugzilla.gnome.org/show_bug.cgi?id=758026

 src/nautilus-files-view.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)
---
diff --git a/src/nautilus-files-view.c b/src/nautilus-files-view.c
index 683bd51..38b1800 100644
--- a/src/nautilus-files-view.c
+++ b/src/nautilus-files-view.c
@@ -1141,13 +1141,19 @@ nautilus_files_view_preview_files (NautilusFilesView *view,
                                    GArray            *locations)
 {
         gchar *uri;
-        guint xid;
+        guint xid = 0;
         GtkWidget *toplevel;
+        GdkWindow *window;
 
         uri = nautilus_file_get_uri (files->data);
         toplevel = gtk_widget_get_toplevel (GTK_WIDGET (view));
 
-        xid = gdk_x11_window_get_xid (gtk_widget_get_window (toplevel));
+#ifdef GDK_WINDOWING_X11
+        window = gtk_widget_get_window (toplevel);
+        if (GDK_IS_X11_WINDOW (window))
+          xid = gdk_x11_window_get_xid (gtk_widget_get_window (toplevel));
+#endif
+
         nautilus_previewer_call_show_file (uri, xid, TRUE);
 
         g_free (uri);