private void bindingNavigatorAddNewItem_Click(object sender, EventArgs e)
{
if (DGVKhachHang.RowCount == 0)
{
BindingNavigatorKhachHang.Enabled = true;
}
DataRow m_Row = m_KhachHangCtrl.ThemDongMoi();
m_Row["MaKH"] = "KH" + m_QuyDinh.LaySTT(DGVKhachHang.Rows.Count + 1);;
m_Row["HoTen"] = "";
m_Row["DiaChi"] = "";
m_Row["DienThoai"] = "";
m_KhachHangCtrl.ThemMoi(m_Row);
BindingNavigatorKhachHang.BindingSource.MoveLast();
}