Using CMemDC in a custom control

Hi. I have have created a listcrtl (derived from CListCtrl) which can
add a progress-bar a cell.

However, the progress control flickers a lot when drawing. I wish to
use CMemDC to reduce flicking (works well on my dialogs etc) but I
can't get it to work right. What do I need to do?

void CMyListCtrl::DrawProgress(int nItem, CDC *pDC, CRect& rect)
{
    // fill interior with light gray
    pDC->FillSolidRect(rect, RGB(242,242,242));

    // draw border
    pDC->Draw3dRect(&rect, RGB(0,0,0), RGB(0,0,0));

    int nProgressPercent = Group[nItem].PC;
    if (nProgressPercent>0){
        // draw progress bar
        CRect LeftRect;
        LeftRect = rect;
        LeftRect.left += 1;
        LeftRect.top += 1;
        LeftRect.bottom -= 1;
        int w = (LeftRect.Width() * nProgressPercent) / 100;
        LeftRect.right = LeftRect.left + w - 1;
        pDC->FillSolidRect(LeftRect, RGB(255,0,0));
    }
}

DrawProgress() is called from OnCustomdraw()

void CSizeRatioListCtrl::OnCustomdraw(NMHDR* pNMHDR, LRESULT* pResult)
{
   MLVCUSTOMDRAW* pLVCD = reinterpret_cast<NMLVCUSTOMDRAW*>( pNMHDR );
   *pResult = CDRF_DODEFAULT;

   int nItem = static_cast<int> (pLVCD->nmcd.dwItemSpec);
   int nSubItem = pLVCD->iSubItem;

   CDC* pDC = CDC::FromHandle(pLVCD->nmcd.hdc);
   CRect rect;
   GetSubItemRect(nItem, nSubItem, LVIR_BOUNDS, rect);

   DrawProgress(nItem, nSubItem, pDC, rect);

   *pResult = CDRF_SKIPDEFAULT;
}