[gtk+/gtk-3-8] Fix gtk_window_set_opacity()

[Alexander Larsson <alexl src gnome org>]

commit 0104f5c1bdc837c473e067875c6bb334da64cf55
Author: Alexander Larsson <alexl redhat com>
Date:   Thu Apr 4 15:38:40 2013 +0200

    Fix gtk_window_set_opacity()
    
    We *do* want to call gdk_window_set_opacity() on toplevels, because
    this particular case does work.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=697263

 gtk/gtkwidget.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 44755b6..6481c50 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -14255,7 +14255,8 @@ gtk_widget_propagate_alpha (GtkWidget *widget)
 
   if (gtk_widget_get_has_window (widget))
     {
-      if (priv->window != NULL && !gdk_window_has_native (priv->window))
+      if (priv->window != NULL &&
+         (!gdk_window_has_native (priv->window) || gtk_widget_is_toplevel (widget)))
        gdk_window_set_opacity (priv->window,
                                norender ? 0 : priv->alpha / 255.0);
     }