/// <summary>
        /// Constructor fills in the menu contents.
        /// </summary>
        public MainMenuScreen()
            : base("")
        {
            // Create our menu entries.
            MenuEntry playGameMenuEntry = new MenuEntry("Play Game");
            MenuEntry optionsMenuEntry = new MenuEntry("Options");
            MenuEntry creditsMenuEntry = new MenuEntry("Credits");
            MenuEntry controlsMenuEntry = new MenuEntry("Controls");
            MenuEntry helpMenuEntry = new MenuEntry("How to Play");
            MenuEntry exitMenuEntry = new MenuEntry("Exit");

            // Hook up menu event handlers.
            playGameMenuEntry.Selected += PlayGameMenuEntrySelected;
            optionsMenuEntry.Selected += OptionsMenuEntrySelected;
            creditsMenuEntry.Selected += CreditsMenuEntrySelected;
            controlsMenuEntry.Selected += ControlsMenuEntrySelected;
            helpMenuEntry.Selected += helpMenuEntrySelected;
            exitMenuEntry.Selected += OnCancel;

            // Add entries to the menu.
            MenuEntries.Add(playGameMenuEntry);
            MenuEntries.Add(optionsMenuEntry);
            MenuEntries.Add(creditsMenuEntry);
            MenuEntries.Add(controlsMenuEntry);
            MenuEntries.Add(helpMenuEntry);
            MenuEntries.Add(exitMenuEntry);
        }
        /// <summary>
        /// Constructor lets the caller specify whether to include the standard
        /// "A=ok, B=cancel" usage text prompt.
        /// </summary>
        public MessageBoxScreen(string message, bool includeUsageText)
            : base(message)
        {
            this.message = message;

            // Create our menu entries.
            MenuEntry yesMenuEntry = new MenuEntry("Yes");
            MenuEntry noMenuEntry = new MenuEntry("No");

            // Hook up menu event handlers.
            yesMenuEntry.Selected += YesMenuEntrySelected;
            noMenuEntry.Selected += OnCancel;

            // Add entries to the menu.
            MenuEntries.Add(yesMenuEntry);
            MenuEntries.Add(noMenuEntry);

            IsPopup = true;

            TransitionOnTime = TimeSpan.FromSeconds(0.2);
            TransitionOffTime = TimeSpan.FromSeconds(0.2);
        }