private void mnQLPhong_Click(object sender, System.EventArgs e)
        {
            frmSDDichVu f = new frmSDDichVu();

            f.MdiParent = this;
            f.Show();
        }
 private void mnQLPhong_Click(object sender, System.EventArgs e)
 {
     frmSDDichVu f = new frmSDDichVu();
     f.MdiParent=this;
     f.Show();
 }