var currentImage = null;
        var arrayImages = new Array();
        
        function ShowImage(name)
        {
            if (currentImage != null)
            {
                HideImage();
            }
            document.getElementById("divCurtain").style.display = "block";
            document.getElementById("divImageInfo" + name).style.display = "none";
            currentImage = name;
            document.getElementById("divImageInfo" + name).style.display = "block";
        }
        
        function HideImage()
        {
            document.getElementById("divCurtain").style.display = "none";
            if (currentImage != null)
            {
                document.getElementById("divImageInfo" + currentImage).style.display = "none";
                currentImage = null;
            }
        }
        
        function ShowNextImage()
        {
            for (var i=0;i<arrayImages.length;i++)
            {
                if (currentImage == arrayImages[i])
                {
                    if (i+1 == arrayImages.length)
                    {
                        ShowImage(arrayImages[0]);
                    } else {
                        ShowImage(arrayImages[i+1]);
                    }
                    return;
                }
            }
        }
        
        function ShowPreviousImage()
        {
            for (var i=0;i<arrayImages.length;i++)
            {
                if (currentImage == arrayImages[i])
                {
                    if (i == 0)
                    {
                        ShowImage(arrayImages[arrayImages.length-1]);
                    } else {
                        ShowImage(arrayImages[i-1]);
                    }
                    return;
                }
            }        
        }
        
        function HandleKeyEvent(evt)
        {
            var pressedKey;
            
            if (currentImage == null) return;
            
            if (window.event)
            {
                pressedKey = event.keyCode;
            }
            else if(evt.which) 
            {
                pressedKey = evt.which;
            }
            switch (pressedKey)
            {
                case 37:
                    ShowPreviousImage();
                    break;
                case 39: 
                    ShowNextImage();
                    break;
                case 27:
                    HideImage();
                    break;
            }
        }
        
        document.onkeydown = HandleKeyEvent;