How to make the group-box text background transparent

HBRUSH CMyDialog::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
   HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);
   if(bSetBkTransparent_)
   {
      pDC->SetBkMode(TRANSPARENT);
      hbr = (HBRUSH)GetStockObject(NULL_BRUSH);
   }


   return hbr;
}