/// <summary>
 /// When image is selected enable/disable setting
 /// </summary>
 /// <param name="sender"></param>
 /// <param name="e"></param>
 private void selectedImageList_SelectionChanged(object sender, SelectionChangedEventArgs e)
 {
     if (slideshowImageList.SelectedItem != null)
     {
         int index = slideshowImageList.SelectedIndex;
         buttonRemoveImage.IsEnabled = true;
         textBoxImageText.IsEnabled  = true;
         textBoxImageText.Text       = selectedSlideShow.GetDescription(index);
         if (selectedSlideShow.GetAt(index) is ImageData)
         {
             textBoxDuration.IsEnabled = true;
             textBoxDuration.Text      = selectedSlideShow.GetDuration(index).ToString();
         }
     }
     else
     {
         buttonRemoveImage.IsEnabled = false;
         textBoxImageText.Text       = string.Empty;
         textBoxImageText.IsEnabled  = false;
         textBoxDuration.Text        = string.Empty;
         textBoxDuration.IsEnabled   = false;
     }
 }