//when the window loads
        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            combo_rating.ItemsSource = FillComboBox();

            //Create new books
            BookRead b1 = new BookRead("The Stand", "Stephen King", 8);
            BookRead b2 = new BookRead("Blood of Elves", "Andrzej Sapkowski", 8);
            BookRead b3 = new BookRead("Neuromancer", "William Gibson", 6);
            BookRead b4 = new BookRead("Jade City", "Fonda Lee", 9);

            Book tbr1 = new Book("Jade War", "Fonda Lee");
            Book tbr2 = new Book("It", "Stephen King");
            Book tbr3 = new Book("Baptism of Fire", "Andrzej Sapkowski");

            //Add books to list
            booksRead.Add(b1);
            booksRead.Add(b2);
            booksRead.Add(b3);
            booksRead.Add(b4);

            booksTBR.Add(tbr1);
            booksTBR.Add(tbr2);
            booksTBR.Add(tbr3);

            dataGrid_read.ItemsSource = booksRead;
            dataGrid_tbr.ItemsSource  = booksTBR;
        }
 //Add a new book from the bottom left UI
 private void btn_addBook_Click(object sender, RoutedEventArgs e)
 {
     //If it's read
     if (radio_read.IsChecked == true)
     {
         BookRead bookRead = new BookRead();
         bookRead.Title  = tbx_title.Text;
         bookRead.Author = tbx_author.Text;
         bookRead.Rating = (byte)combo_rating.SelectedItem;
         booksRead.Add(bookRead);
     }
     //If it's not read
     else if (radio_tbr.IsChecked == true)
     {
         Book book = new Book();
         book.Title  = tbx_title.Text;
         book.Author = tbx_author.Text;
         booksTBR.Add(book);
     }
     //Clear the text boxes
     tbx_title.Clear();
     tbx_author.Clear();
     combo_rating.SelectedIndex = 0;
     Update();               //Resets the dataGrid ItemSource
 }