window: update setting when the view changes

Note: Eventually I ended reverting the changes I have made here a few
commits back.

src/gcal-window.c

@@ -461,6 +461,8 @@ view_changed (GObject    *object,
   g_type_class_unref (eklass);
 
   priv->active_view = view_type;
+  g_object_notify (G_OBJECT (user_data), "active-view");
+
   update_view (GCAL_WINDOW (user_data));
 }