Problem in resizing with scroll bar

From:

Mohit <behappy.mohit@gmail.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Tue, 23 Jun 2009 10:10:58 -0700 (PDT)

Message-ID:

<225e9e78-9b89-45cf-a90d-f687309474de@x6g2000prc.googlegroups.com>

Hi,
I m making dialog based application .I am trying to make resizable
dialog with scroll bar.I had put maximum and minimum size in
void CMainDlg::OnGetMinMaxInfo(MINMAXINFO* lpMMI)
{
        lpMMI->ptMinTrackSize.x=710;
lpMMI->ptMinTrackSize.y=335;

lpMMI->ptMaxTrackSize.x =710;
    lpMMI->ptMaxTrackSize.y =675;

    CDialog::OnGetMinMaxInfo(lpMMI);
}
Vertical scroll coding
void CMainDlg::OnVScroll(UINT nSBCode, UINT nPos, CScrollBar*
pScrollBar)
{
    int nDelta;
    int nMaxPos = m_rect.Height() - m_nCurHeight;

    {switch (nSBCode)
    {
    case SB_LINEDOWN:
        if (m_nScrollPos >= nMaxPos)
            return;
        nDelta = min(nMaxPos/100,nMaxPos-m_nScrollPos);
        break;

    case SB_LINEUP:
        if (m_nScrollPos <= 0)
            return;
        nDelta = -min(nMaxPos/100,m_nScrollPos);
        break;

         case SB_PAGEDOWN:
        if (m_nScrollPos >= nMaxPos)
            return;
        nDelta = min(nMaxPos/10,nMaxPos-m_nScrollPos);
        break;

    case SB_THUMBPOSITION:
        nDelta = (int)nPos - m_nScrollPos;
        break;

    case SB_PAGEUP:
        if (m_nScrollPos <= 0)
            return;
        nDelta = -min(nMaxPos/10,m_nScrollPos);
        break;

         default:
        return;
    }
    m_nScrollPos += nDelta;
    SetScrollPos(SB_VERT,m_nScrollPos,TRUE);
    ScrollWindow(0,-nDelta);
    }
    CDialog::OnVScroll(nSBCode, nPos, pScrollBar);

}
My maximun size is default dialog size
My problem is when i decrease size of dialog and scroll down then
increas size vertically
Then some extra dialog start appearing which i dont want.
Can any body suggest me how can i solve my problem

Mohit