//书籍添加事件
private void ToolStripButtonBookAdd_Click(object sender, EventArgs e)
{
BookAdd bookAdd = new BookAdd();
bookAdd.MdiParent = this;
bookAdd.Show();
}
private void button4_Click(object sender, EventArgs e)
{
BookAdd bookAdd = new BookAdd();
this.Hide();
bookAdd.Show();
}
