/// <summary>
 /// Responds to user input, accepting or cancelling the message box.
 /// </summary>
 public override void HandleInput(InputHelper input, GameTime gameTime)
 {
     if (input.IsMenuSelect() || input.IsMenuCancel() ||
         input.IsNewMouseButtonPress(MouseButtons.LeftButton))
     {
         ExitScreen();
     }
 }
        /// <summary>
        /// Responds to user input, changing the selected entry and accepting
        /// or cancelling the menu.
        /// </summary>
        public override void HandleInput(InputHelper input, GameTime gameTime)
        {
            // Mouse or touch on a menu item
            int hoverIndex = GetMenuEntryAt(input.Cursor);
            if (hoverIndex > -1 && _menuEntries[hoverIndex].IsSelectable() && !_scrollLock)
            {
                _selectedEntry = hoverIndex;
            }
            else
            {
                _selectedEntry = -1;
            }

            _scrollSlider.Hover = false;
            if (input.IsCursorValid)
            {
                _scrollUp.Collide(input.Cursor);
                _scrollDown.Collide(input.Cursor);
                _scrollSlider.Collide(input.Cursor);
            }
            else
            {
                _scrollUp.Hover = false;
                _scrollDown.Hover = false;
                _scrollLock = false;
            }

            // Accept or cancel the menu?
            if (input.IsMenuSelect() && _selectedEntry != -1)
            {
                if (_menuEntries[_selectedEntry].IsExitItem())
                {
                    ScreenManager.Game.Exit();
                }
                else if (_menuEntries[_selectedEntry].Screen != null)
                {
                    ScreenManager.AddScreen(_menuEntries[_selectedEntry].Screen);
                    if (_menuEntries[_selectedEntry].Screen is IDemoScreen)
                    {
                        ScreenManager.AddScreen(
                            new MessageBoxScreen((_menuEntries[_selectedEntry].Screen as IDemoScreen).GetDetails()));
                    }
                }
            }
            else if (input.IsMenuCancel())
            {
                ScreenManager.Game.Exit();
            }

            if (input.IsMenuPressed())
            {
                if (_scrollUp.Hover)
                {
                    _menuOffset = Math.Max(_menuOffset - 200f * (float)gameTime.ElapsedGameTime.TotalSeconds, 0f);
                    _scrollLock = false;
                }
                if (_scrollDown.Hover)
                {
                    _menuOffset = Math.Min(_menuOffset + 200f * (float)gameTime.ElapsedGameTime.TotalSeconds, _maxOffset);
                    _scrollLock = false;
                }
                if (_scrollSlider.Hover)
                {
                    _scrollLock = true;
                }
            }
            if (input.IsMenuReleased())
            {
                _scrollLock = false;
            }
            if (_scrollLock)
            {
                _scrollSlider.Hover = true;
                _menuOffset = Math.Max(Math.Min(((input.Cursor.Y - _menuBorderTop) / (_menuBorderBottom - _menuBorderTop)) * _maxOffset, _maxOffset), 0f);
            }
        }