[gnome-desktop] gnome-bg: force property update when doing new crossfade frame

[Cosimo Cecchi <cosimoc src gnome org>]

commit e36d931ca2aad168427e22d23f9013316854370e
Author: Ray Strode <rstrode redhat com>
Date:   Mon Feb 7 13:56:41 2011 -0500

    gnome-bg: force property update when doing new crossfade frame
    
    gnome-shell needs to get notified about animation updates.
    
    This commit frobs the property to wake mutter up.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=641526

 libgnome-desktop/gnome-bg-crossfade.c |   17 +++++++++++++++++
 1 files changed, 17 insertions(+), 0 deletions(-)
---
diff --git a/libgnome-desktop/gnome-bg-crossfade.c b/libgnome-desktop/gnome-bg-crossfade.c
index 02a120e..8a4778c 100644
--- a/libgnome-desktop/gnome-bg-crossfade.c
+++ b/libgnome-desktop/gnome-bg-crossfade.c
@@ -371,6 +371,20 @@ animations_are_disabled (GnomeBGCrossfade *fade)
 }
 
 static void
+send_root_property_change_notification (GnomeBGCrossfade *fade)
+{
+        long zero_length_pixmap;
+
+        /* We do a zero length append to force a change notification,
+         * without changing the value */
+        XChangeProperty (GDK_WINDOW_XDISPLAY (fade->priv->window),
+                         GDK_WINDOW_XID (fade->priv->window),
+                         gdk_x11_get_xatom_by_name ("_XROOTPMAP_ID"),
+                         XA_PIXMAP, 32, PropModeAppend,
+                         (guchar *) &zero_length_pixmap, 0);
+}
+
+static void
 draw_background (GnomeBGCrossfade *fade)
 {
 	if (gdk_window_get_window_type (fade->priv->window) == GDK_WINDOW_ROOT) {
@@ -380,6 +394,9 @@ draw_background (GnomeBGCrossfade *fade)
                             gdk_window_get_width (fade->priv->window),
                             gdk_window_get_height (fade->priv->window),
                             False);
+
+                send_root_property_change_notification (fade);
+
 		gdk_flush ();
 	} else {
 		gdk_window_invalidate_rect (fade->priv->window, NULL, FALSE);