protected void OpenTitleScreen()
 {
     CurrentScreen = ScreenState.Title;
     SearchButton.MoveToStart();
     StartButton.MoveToStart();
     Title.MoveTo(CenterPos);
 }

        /* Layer Update - control transition percentage
         * call via base.Update 
         */
        public virtual void Update(float ms)
        {
            switch (state)
            {
                // TransitioningOn : update transition progress, if complete, switch to active
                case ScreenState.TransitioningOn:
                    if (UpdateTransition(ms, transitionOnTime, 1))
                    {
                        state = ScreenState.TransitioningOn;                        
                    }
                    else
                    {                        
                        state = ScreenState.Active;
                        if (fadeInCompleteCallback != null) fadeInCompleteCallback();
                    }
                    break;

                case ScreenState.Active:
                    break;

                case ScreenState.TransitioningOff:
                    if (UpdateTransition(ms, transitionOffTime, -1))
                    {
                        state = ScreenState.TransitioningOff;
                    }
                    else
                    {
                        state = ScreenState.Hidden;
                        if (fadeOutCompleteCallback != null) fadeOutCompleteCallback();
                        //mustExit = true;
                        //Globals.screenManager.Pop();
                    }
                    break;
            }
        }

        public void SetScreenState(ScreenState state)
        {
            if (state == ScreenState.WarningNext && _longWarningNext == null)
                return;
            if (state == ScreenState.WarningPrevious && _longWarningPrevious == null)
                return;
            _screenState = state;

        }

 public GameScreen()
 {
     screenState = ScreenState.TransitionOn;
     transitionOnTime = TimeSpan.Zero;
     transitionOffTime = TimeSpan.Zero;
     transitionProgress = 0;
     alwaysVisible = false;
     isPopup = false;
     isExiting = false;
 }

        /// <summary>
        /// Initialize a new instance of the ExerciseScreen class.
        /// </summary>
        /// <param name="game">The related game object.</param>
        /// <param name="viewableArea">The desired canvas size to draw on.</param>
        /// <param name="startingState">The desired starting Screen State</param>
        public LoadingScreen(Game game, Rectangle viewableArea, ScreenState startingState)
            : base(game)
        {
            ScreenState = startingState;
            _viewableArea = viewableArea;

            Title = "Loading";

            _isInitialized = false;
        }

 public ScreenManager()
 {
     mScreens = new List<Screen>();
     GameScreen gameScreen = new GameScreen();
     MenuScreen menuScreen = new MenuScreen();
     mCurrentScreen = gameScreen;
     AddScreen(menuScreen);
     AddScreen(gameScreen);
     mScreenState = ScreenState.Playing;
 }

 protected Screen()
 {
     _state = ScreenState.FadingIn;
     _isExiting = false;
     _isCovered = false;
     _hasInputFocus = false;
     _transition = 1;
     _transitionOnTime = TimeSpan.Zero;
     _transitionOffTime = TimeSpan.Zero;
 }

 private void updateScreenState()
 {
     if (State == ScreenState.Exiting && TransitionAlpha <= 0)
     {
         RemoveScreen();
     }
     else if (State == ScreenState.Entering && TransitionAlpha >= 1.0f)
     {
         State = ScreenState.Active;
     }
 }

        public void OpenNewScreen(ScreenState newState, bool clear = true)
        {
            previousState = screenState;
            screenState = newState;

            if (clear)
            {
                screenList[(int)previousState].Clear();
                screenList[(int)screenState].Initialize();
            }
        }

 IEnumerator EnterCreditsCoroutine()
 {
     screenState = ScreenState.CREDITS;
     yield return StartCoroutine(SceneManager.instance.fade_black());
     yield return StartCoroutine(SoundManager.instance.FadeOutAudioSource(soundtrack(), rate: 0.1f));
     Application.LoadLevel(SceneManager.SCENE_CREDITS);
     yield return StartCoroutine(SceneManager.instance.fade_out());
     yield return null;
     GameManager.instance.Play();
     yield break;
 }

    IEnumerator EnterGameCoroutine()
    {
        screenState = ScreenState.GAME;
        GameManager.instance.SetTime(GameManager.TimeType.SET, startTime);
        StartCoroutine(SoundManager.instance.FadeOutAudioSource(soundtrack(), rate: 0.1f));
        GameManager.instance.LoadPlayerData();
        yield return StartCoroutine(SceneManager.instance.LoadSceneCoroutine(startScene));
        GameManager.instance.MenuLayout.GetComponent<Menu_Layout>().GameMenus(true);

        Destroy(this.gameObject);
        yield break;
    }

        private void ChangeScreen(ScreenState screenState, CreateScreen createScreen)
        {
            previousScreen = currentScreen;

            if (!screens.ContainsKey(screenState))
            {
                screens.Add(screenState, createScreen());
                screens[screenState].LoadContent();
            }
            currentScreen = screens[screenState];
            currentScreen.Activate();
        }

    IEnumerator EnterAlfredCoroutine()
    {
        screenState = ScreenState.GAME;
        GameManager.instance.SetTime(GameManager.TimeType.SET, 20);
        GameManager.instance.playerData.daysPassed = 1;
        StartCoroutine(SoundManager.instance.FadeOutAudioSource(soundtrack(), rate: 0.1f));
        yield return StartCoroutine(SceneManager.instance.LoadSceneCoroutine("G_MainStreet"));
        GameManager.instance.MenuLayout.GetComponent<Menu_Layout>().GameMenus(true);

        Destroy(this.gameObject);
        yield break;
    }

        SpriteFont text; // font for level select

        #endregion Fields

        #region Constructors

        public LevelSelect(Dictionary<string, Texture2D> imgs, SpriteFont txt, int cLV, int mLV)
        {
            images = imgs;
            text = txt;
            currentLevel = cLV;
            maxLevel= mLV;
            screenState = new ScreenState();
            screenState = ScreenState.Select;
            cleared = new Dictionary<int, bool>();
            for (int i = 0; i < maxLevel; i++)
            {
                cleared.Add((i + 1), false);
            }
        }

    void Start()
    {
        spRender = gameObject.GetComponent<SpriteRenderer>();
        screenMap = new Dictionary<MenuState, ScreenState>();

        screenMap.Add( MenuState.Main		 , new MenuScreen( skin, spRender, this ) );
        screenMap.Add( MenuState.PlayMode	 , new PlayModeScreen( skin, spRender, this ) );
        screenMap.Add( MenuState.Credits	 , new CreditScreen( skin, spRender, this ) );
        screenMap.Add( MenuState.Instructions, new InstructionScreen( skin, spRender, this ) );

        currentScreen = screenMap[ MenuState.Main ];

        spRender.sprite = currentScreen.Background;
    }

        private void ChangeScreen(ScreenState screenState)
        {
            switch (screenState)
            {
                case ScreenState.Title:
                    {
                        ChangeScreen(screenState, new CreateScreen(CreateTitleScreen));
                        break;
                    }

                case ScreenState.Options:
                    {
                        ChangeScreen(screenState, new CreateScreen(CreateOptionScreen));
                        break;
                    }

                case ScreenState.Gameplay:
                    {
                        ChangeScreen(screenState, new CreateScreen(CreateGameplayScreen));
                        break;
                    }

                case ScreenState.GameOver:
                    {
                        ChangeScreen(screenState, new CreateScreen(CreateGameOverScreen));
                        break;
                    }

                case ScreenState.GameWin:
                    {
                        ChangeScreen(screenState, new CreateScreen(CreateGameWinScreen));
                        break;
                    }

                case ScreenState.PreviousScreen:
                    {
                        currentScreen = previousScreen;
                        currentScreen.Activate();
                        break;
                    }

                case ScreenState.Exit:
                    {
                        game.Exit();
                        break;
                    }

            }
        }

 private void Bai04_Load(object sender, EventArgs e)
 {
     UserCT = new UserControl[4];
     nUserCT = 4;
     UserCT[0] = new Phan1.Bai4.BaiTap12();
     UserCT[1] = new Phan1.Bai4.BaiTap34();
     UserCT[2] = new Phan1.Bai4.LuyenTap();
     UserCT[3] = new Phan1.Bai4.LyThuyet();
     for (int i = 0; i < nUserCT; i++)
     {
         pnBai1.Controls.Add(UserCT[i]);
         UserCT[i].Dock = DockStyle.Fill;
     }
     currentState = ScreenState.Temp;
     UpdateScreen();
 }

 private void ListenForScreenEvents()
 {
     if(Keyboard.GetState().IsKeyDown(Keys.Escape) && mPreviousKeyboardState.IsKeyUp(Keys.Escape))
     {
         if(mScreenState == ScreenState.Playing)
         {
             mScreenState = ScreenState.Paused;
             mCurrentScreen = mScreens.Where(s => s.GetType() == typeof(MenuScreen)).Select(s => s as MenuScreen).FirstOrDefault();
         }
         else if(mScreenState == ScreenState.Paused)
         {
             mScreenState = ScreenState.Playing;
             mCurrentScreen = mScreens.Where(s => s.GetType() == typeof(GameScreen)).Select(s => s as GameScreen).FirstOrDefault();
         }
     }
     mPreviousKeyboardState = Keyboard.GetState();
 }

        private void Bai11_Load(object sender, EventArgs e)
        {
            nUsct = 4;
            myUsercontrol = new UserControl[5];

            myUsercontrol[0] = new Phan1.Bai_11.BaiTap1();
            myUsercontrol[1] = new Phan1.Bai_11.BaiTap2();
            myUsercontrol[2] = new Phan1.Bai_11.BaiTap3();
            myUsercontrol[3] = new Phan1.Bai_11.BaiTap4();

            for (int i = 0; i < nUsct; i++)
            {
                pnbai11.Controls.Add(myUsercontrol[i]);
                myUsercontrol[i].Dock = DockStyle.Fill;
            }
            currentScreen = ScreenState.ChonBT;
            UpdateScreen();
        }

        private void Bai01_Load(object sender, EventArgs e)
        {
            UserCT = new UserControl[5];
            nUserCT = 5;
            UserCT[0] = new PHAN1.Bai1.BaiTap1();
            UserCT[1] = new PHAN1.Bai1.BaiTap2();
            UserCT[2] = new PHAN1.Bai1.BaiTap3();
            UserCT[3] = new PHAN1.Bai1.BaiTap4();
            UserCT[4] = new PHAN1.Bai1.BaiTap5();

            for (int i = 0; i < nUserCT; i++)
            {
               pnBaiTap.Controls.Add(UserCT[i]);
                UserCT[i].Dock = DockStyle.Fill;
            }
            currentState = ScreenState.Temp;
            UpdateScreen();
        }