[gnome-sudoku/gnome-3-20] Fix window size growing out of control with GTK+ 3.20

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 5d596dde1067d50054aa7b150a3f11abed601198
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sun May 22 17:54:56 2016 -0500

    Fix window size growing out of control with GTK+ 3.20

 src/gnome-sudoku.vala |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)
---
diff --git a/src/gnome-sudoku.vala b/src/gnome-sudoku.vala
index 6a57c86..8872723 100644
--- a/src/gnome-sudoku.vala
+++ b/src/gnome-sudoku.vala
@@ -258,8 +258,7 @@ public class Sudoku : Gtk.Application
     {
         if (is_maximized || is_tiled)
             return;
-        window_width = allocation.width;
-        window_height = allocation.height;
+        window.get_size (out window_width, out window_height);
     }
 
     private bool window_state_event_cb (Gdk.EventWindowState event)