[mutter] theme: Add the .background style class back to frames

[Jasper St. Pierre <jstpierre src gnome org>]

commit 47be4fdf07f701add59d5acf5c7dd228064f9924
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Thu Jan 10 16:17:29 2013 -0500

    theme: Add the .background style class back to frames
    
    GtkWindow added the BACKGROUND style class to all windows, which the
    CSS file selects on to set a background color for all windows. Without
    this, the background color becomes undefined, and thus window frames
    look like they have "glitchy" graphics.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=690317

 src/ui/theme.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/ui/theme.c b/src/ui/theme.c
index f68fadc..67697ec 100644
--- a/src/ui/theme.c
+++ b/src/ui/theme.c
@@ -5454,6 +5454,7 @@ meta_theme_create_style_context (GdkScreen   *screen,
   style = gtk_style_context_new ();
   path = gtk_widget_path_new ();
   gtk_widget_path_append_type (path, META_TYPE_FRAMES);
+  gtk_widget_path_iter_add_class (path, -1, GTK_STYLE_CLASS_BACKGROUND);
   gtk_style_context_set_path (style, path);
   gtk_widget_path_unref (path);