private void ClickAgregar(object sender, RoutedEventArgs e)
        {
            var ventana = new DetalleLibro();

            ventana.Owner = Window.GetWindow(this);
            ventana.ShowDialog();
            ActualizarLibros();
        }
        private void Seleccionar(object sender, MouseButtonEventArgs e)
        {
            var ventana = new DetalleLibro();

            ventana.Libro = (sender as ListViewItem).Content as Modelos.Libro;
            ventana.Owner = Window.GetWindow(this);
            ventana.ShowDialog();
            ActualizarLibros();
        }