/// <summary>
        /// Handle a RenderOrderAction that the LayerManager couldn't identify what to do with.
        /// Implement this if you have RenderOrderActions that aren't one of the builtin types.
        /// </summary>
        /// <param name="action"></param>
        protected virtual void HandleUnknownRenderOrderAction(RenderOrder.AbstractRenderOrderAction action)
        {
            var name = Enum.GetName(typeof(RenderOrder.RenderOrderActionType), action.ActionType);

            throw new RenderOrderException(
                      string.Format(
                          "The RenderOrderAction '{0}' cannot be used in the RenderOrder for a LayerManager.",
                          name == null ? action.ActionType : (object)name, action.ActionType));
        }
 /// <summary>
 /// Handle a RenderOrderAction that the RenderLayer couldn't identify what to do with.
 /// Implement this if you have RenderOrderActions that aren't one of the builtin types.
 /// </summary>
 /// <param name="action"></param>
 protected virtual void HandleUnknownRenderOrderAction(
     RenderOrder.AbstractRenderOrderAction action, RenderableHandler renderAction)
 {
     throw new RenderOrderException(
               String.Format("Unknown render order action '{0}'.", action));
 }