[gtk+] Create the icon pixmap with the system visual

[Matthias Clasen <matthiasc src gnome org>]

commit a4d59f7415968e2cd2d6bb0cff97dffaff022f2e
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Sun Nov 14 09:38:32 2010 -0500

    Create the icon pixmap with the system visual
    
    Since what we are doing is turning an icon with alpha into a
    no-alpha icon + mask for legacy window managers, it makes more sense
    to use the system visual than the window's visual, which might
    be ARGB.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=634821

 gdk/x11/gdkwindow-x11.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/gdk/x11/gdkwindow-x11.c b/gdk/x11/gdkwindow-x11.c
index 88d8510..b369e2c 100644
--- a/gdk/x11/gdkwindow-x11.c
+++ b/gdk/x11/gdkwindow-x11.c
@@ -271,16 +271,17 @@ _gdk_x11_window_create_bitmap_surface (GdkWindow *window,
   return surface;
 }
 
+/* Create a surface backed with a pixmap without alpha on the same screen as window */
 static cairo_surface_t *
 gdk_x11_window_create_pixmap_surface (GdkWindow *window,
                                       int        width,
                                       int        height)
 {
+  GdkScreen *screen = gdk_window_get_screen (window);
+  GdkVisual *visual = gdk_screen_get_system_visual (screen);
   cairo_surface_t *surface;
   Pixmap pixmap;
-  GdkVisual *visual;
 
-  visual = gdk_window_get_visual (window);
   pixmap = XCreatePixmap (GDK_WINDOW_XDISPLAY (window),
                           GDK_WINDOW_XID (window),
                           width, height,