private void frmDM_QuyenHoaDon_OnThemMoi(object sender, EventArgs e)
        {
            isAdd = true;
            frmChiTiet_QuyenHoaDon frm = new frmChiTiet_QuyenHoaDon(this);

            frm.ShowDialog();
        }
 private void frmDM_QuyenHoaDon_OnGridDoubleClick(object sender, EventArgs e)
 {
     if (kyhieuhoadon != "")
     {
         isAdd = false;
         frmChiTiet_QuyenHoaDon frm = new frmChiTiet_QuyenHoaDon(this);
         frm.ShowDialog();
     }
 }