/// <summary>
        /// Responds to user input, accepting or cancelling the message box.
        /// </summary>
        public override void HandleInput(InputState input)
        {
            PlayerIndex playerIndex;

            // We pass in our ControllingPlayer, which may either be null (to
            // accept input from any player) or a specific index. If we pass a null
            // controlling player, the InputState helper returns to us which player
            // actually provided the input. We pass that through to our Accepted and
            // Cancelled events, so they can tell which player triggered them.
            if (input.IsMenuSelect(ControllingPlayer, out playerIndex))
            {
                // Raise the accepted event, then exit the message box.
                if (Accepted != null)
                {
                    Accepted(this, new PlayerIndexEventArgs(playerIndex));
                }
                ExitScreen();
            }
            else if (input.IsMenuCancel(ControllingPlayer, out playerIndex))
            {
                // Raise the cancelled event, then exit the message box.
                if (Cancelled != null)
                {
                    Cancelled(this, new PlayerIndexEventArgs(playerIndex));
                }
                ExitScreen();
            }
        }
        /// <summary>
        /// Lets the game respond to player input. Unlike the Update method,
        /// this will only be called when the gameplay screen is active.
        /// </summary>
        public override void HandleInput(InputState input)
        {
            if (input == null)
            {
                return;
            }
            if (ControllingPlayer == null)
            {
                return;
            }

            var playerIndex = (int)ControllingPlayer.Value;
            KeyboardState keyboardState = input.CurrentKeyboardStates[playerIndex];
            GamePadState gamePadState = input.CurrentGamePadStates[playerIndex];

            // The game pauses either if the user presses the pause button, or if they unplug the active gamepad.
            bool gamePadDisconnected = !gamePadState.IsConnected && input.GamePadWasConnected[playerIndex];
            if (input.IsPauseGame(ControllingPlayer) || gamePadDisconnected)
            {
                ScreenManager.AddScreen(new PauseMenuScreen(), ControllingPlayer);
            }
        }