how to avoid blinking windows when invisible

void CRecordItemProgressEx::OnDrawCaption(XTP_REPORTRECORDITEM_DRAWARGS* pDrawArgs, XTP_REPORTRECORDITEM_METRICS* pMetrics)
{
 if(!(pDrawArgs && pMetrics))
  return;
 // draw text
 CXTPReportRecordItemText::OnDrawCaption(pDrawArgs, pMetrics);
 if(!m_bUseProgress)
  return;
 CDC* pDC = pDrawArgs->pDC;
 CXTPFontDC font(pDC);
 CRect rcItem = pDrawArgs->rcItem;
 CXTPReportPaintManager* pPaintManager = pDrawArgs->pControl->GetPaintManager();
 
 rcItem.left -= 2;
 rcItem.right += 2;
 rcItem.top -= 1;
 rcItem.bottom += 1;
 pDC->FillSolidRect(rcItem, m_bgColor);
// rcItem.bottom -= 1;
// rcItem.left += 1;  // leave margin in case row is highlighted
//  // draw border
//  pDC->Draw3dRect(&rcItem, RGB(0,0,0), ::GetSysColor(COLOR_BTNSHADOW));
 // draw progress bar and text
 CRect LeftRect, RightRect;
 RightRect = LeftRect = rcItem;
 int w = (LeftRect.Width() * m_nProgress) / 100;
 LeftRect.right = LeftRect.left + w - 1;
 RightRect.left = LeftRect.right;
 pDC->FillSolidRect(LeftRect, m_fgColor); // RGB(160, 32, 240)
 if (m_strProgress != _T(""))
 {
  CString str;
  str.Format(_T("%s %d%%"), m_strProgress, m_nProgress);
  pDC->SetBkMode(TRANSPARENT);
  CRect TextRect;
  TextRect = rcItem;
  TextRect.DeflateRect(1, 1);
  font.SetFont(pPaintManager->GetTextFont());
  CRgn rgn;
  rgn.CreateRectRgn(LeftRect.left, LeftRect.top, LeftRect.right, LeftRect.bottom);
  pDC->SelectClipRgn(&rgn);
  pDC->SetTextColor(RGB(255, 255, 255));
  pDC->DrawText(str, &TextRect, DT_CENTER | DT_NOPREFIX | DT_SINGLELINE);
  rgn.DeleteObject();
  rgn.CreateRectRgn(RightRect.left, RightRect.top, RightRect.right, RightRect.bottom);
  pDC->SelectClipRgn(&rgn);
  pDC->SetTextColor(RGB(0, 0, 0));
  pDC->DrawText(str, &TextRect, DT_CENTER | DT_NOPREFIX | DT_SINGLELINE);
  rgn.DeleteObject();
  pDC->SelectClipRgn(NULL);
 }
}