/// <summary>
 /// The command action to add a book tag.
 /// </summary>
 public void AddBookTagCommandAction(object parameter)
 {
     if (!string.IsNullOrEmpty(BookNewTagText))
     {
         if (!SelectedBookTags.Contains(BookNewTagText))
         {
             SelectedBookTags.Add(BookNewTagText);
             OnPropertyChanged(() => BookDisplayTags);
             BookNewTagText = string.Empty;
         }
     }
 }
 /// <summary>
 /// The command action to clear the book tags.
 /// </summary>
 public void ClearBookTagsCommandAction(object parameter)
 {
     SelectedBookTags.Clear();
     OnPropertyChanged(() => BookDisplayTags);
     BookNewTagText = string.Empty;
 }