private void newBookEntryToolStripMenuItem1_Click(object sender, EventArgs e)
        {
            this.Hide();
            New_entry_book n = new New_entry_book();

            n.Show();
        }
 private void newBookEntryToolStripMenuItem1_Click(object sender, EventArgs e)
 {
     this.Hide();
     New_entry_book n = new New_entry_book();
     n.Show();
 }