private void AddAuthor_Click(object sender, RoutedEventArgs e)
        {
            var vb = new Program.AuthorView();

            if (vb.ShowDialog() == true)
            {
                authorGrid.Items.Refresh();
                dialogresult = true;
            }
        }
        private void authorGrid_MouseDoubleClick(object sender, MouseButtonEventArgs e)
        {
            var vb = new Program.AuthorView((Author)authorGrid.SelectedItem);

            if (vb.ShowDialog() == true)
            {
                authorGrid.Items.Refresh();
                dialogresult = true;
            }
        }