C#

System.Windows.Int32Rect not exist

{
    class Class1
    {
        //method I am Using to Add Books to my Binary File
        internal void AddBooks()
        {
            string addBook = "";
            while (addBook != "No")
            {
                Console.WriteLine("========================================");
                Console.WriteLine("Write the Books Identifiing number u want to add");
                //book number i will need this to count the same books
                int bookNumber = int.Parse(Console.ReadLine());

                Console.WriteLine("Write Books Titttle");
                string bookTittle = Console.ReadLine();

                Console.WriteLine("Write th Authors Name");
                string authorName = Console.ReadLine();

                Console.WriteLine("Write the publishing company ");
                string pubCompany = Console.ReadLine();

                FileStream fsBooks = new FileStream("Books.bin", FileMode.Append, FileAccess.Write);
                BinaryWriter bwBooks = new BinaryWriter(fsBooks);

                bwBooks.Write(bookNumber);
                bwBooks.Write(FillBlanks(bookTittle, 30));
                bwBooks.Write(FillBlanks(bookTittle,25));
                bwBooks.Write(FillBlanks(pubCompany, 15));
                bwBooks.Flush();
                Console.WriteLine("==========================");
                Console.WriteLine("Do You Want to add another Book:  'Yes'/'No' ");
                addBook = Console.ReadLine();
                bwBooks.Close();
                fsBooks.Close();
            }
        }
        static string FillBlanks(string text, int size)
        {
            string blanks = "";

            if (text.Length < size)
            {
                int difference = size - text.Length;
                for (int i = 0; i < difference; i++)
                {
                    blanks += " ";
                }
            }
            else if (text.Length > size)
            {
                text = text.Substring(0, size);
            }
            return text + blanks;
        }
    }
}

<Button x:Name="btnAddSaveUpdate" Content="{Binding AddSaveUpdateContent}"  Style="{StaticResource ButtonStyle}" Command="{Binding AddSaveUpdateCmd}" CommandParameter="AddSaveButton"  />

 _addSaveUpdateCmd = new RelayCommand(param => OnExecute(param), this.CanExecute);
AddSaveUpdateContent = "Add";

case "AddSaveButton":
                    return true;

case "AddSaveButton":
                  PerformButtonTask(AddSaveUpdateContent);
                  break;

case "Add":
     AddSaveUpdateContent = "Save";
     ExitCancelCmdContent = "Cancel";
     ClearFields();
     EnableFieldsEvent(true);
     break;