CFiledialog

Hi, 

I am trying to update my application from vs2005 to vs2012. I am using CFiledialog with multiple file selection flag. 

bVistaStyles is set to true. when i run my application on windows 7 system ,it gives access violation. 

The problem occurs in the following line. GetParent()->m_hWnd  shows null. Why?

UINT nfiles = CommDlg_OpenSave_GetSpec(GetParent()->m_hWnd, &dummy_buffer, 1);

CMultipleFileDialog is derived from CFileDialog

CMultipleFileDialog::CMultipleFileDialog(BOOL bOpenFileDialog, LPCTSTR lpszDefExt, LPCTSTR lpszFileName,
                               DWORD dwFlags, LPCTSTR lpszFilter, CWnd* pParentWnd,DWORD dwSize,BOOL m_bVistaStyle) :
CFileDialog(bOpenFileDialog, lpszDefExt, lpszFileName, dwFlags, lpszFilter, pParentWnd,dwSize,m_bVistaStyle)

 CMultipleFileDialog dlg(TRUE,sDefExt,NULL,OFN_FILEMUSTEXIST|OFN_HIDEREADONLY|OFN_OVERWRITEPROMPT|OFN_ALLOWMULTISELECT|OFN_EXPLORER ,filter,theApp.m_pMainWnd,NULL,TRUE);

void CMultipleFileDialog::OnFileNameChange()
{
    TCHAR dummy_buffer;

    // Get the required size for the 'files' buffer
UINT nfiles = CommDlg_OpenSave_GetSpec(GetParent()->m_hWnd, &dummy_buffer, 1);

    // Get the required size for the 'folder' buffer
    UINT nfolder = CommDlg_OpenSave_GetFolderPath(theMainFrame->m_hWnd, &dummy_buffer, 1);

    // Check if lpstrFile and nMaxFile are large enough
    if (nfiles + nfolder > m_ofn.nMaxFile)
    {
        bParsed = FALSE;
        if (Files)
            delete[] Files;
        Files = new TCHAR[nfiles + 1];
        CommDlg_OpenSave_GetSpec(theMainFrame->m_hWnd, Files, nfiles);

        if (Folder)
            delete[] Folder;
        Folder = new TCHAR[nfolder + 1];
        CommDlg_OpenSave_GetFolderPath(theMainFrame->m_hWnd, Folder, nfolder);
    }