private void newViewToolStripMenuItem_Click(object sender, EventArgs e)
        {
            BookListForm bookListForm = new BookListForm(MainDocument);

            bookListForm.MdiParent = this;
            bookListForm.Show();
            ChangeLayout();
        }
        public MainForm()
        {
            InitializeComponent();
            IsMdiContainer = true;
            BookListForm bookListForm = new BookListForm(MainDocument);

            bookListForm.MdiParent = this;
            bookListForm.Show();
            ChangeLayout();
        }