[gnome-chess] Fix background color regression in 3D view

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 1d080a2716a395a69cd0859a9ab2b4c4ee171861
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sat Nov 2 12:31:58 2013 -0500

    Fix background color regression in 3D view
    
    We've been painting it black since the switch to Gtk.StyleContext, since
    the ChessView's style context does not have a background color.

 src/chess-view-3d.vala |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/chess-view-3d.vala b/src/chess-view-3d.vala
index 6bc6f91..9cf00bb 100644
--- a/src/chess-view-3d.vala
+++ b/src/chess-view-3d.vala
@@ -262,7 +262,8 @@ private class ChessView3D : ChessView
 
         for (var i = 0; i < n_passes; i++)
         {
-            var bg = get_style_context ().get_background_color (get_state_flags ());
+            var window = (Gtk.Window) get_toplevel();
+            var bg = window.get_style_context ().get_background_color (window.get_state_flags ());
             glClearColor ((float) bg.red, (float) bg.green, (float) bg.blue, 1.0f);
             glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);