private void EditAuthor()
        {
            selectedAuthor = dataGridViewAuthors.SelectedRows[0].Tag as Author;
            FormAddorEditNewAuthor newAuthor = new FormAddorEditNewAuthor(authors, selectedAuthor);

            newAuthor.ShowDialog();
            selectedAuthor = null;
        }
        private void AddNewAuthor()
        {
            FormAddorEditNewAuthor newAuthor = new FormAddorEditNewAuthor(authors, selectedAuthor);

            newAuthor.ShowDialog();
        }