CWinApp::OnFileOpen() (New CFileDialog Template)

CWinApp::OnFileOpen() just calls CFileDialog(), if it looks different, its probably because you're using an old version of MFC (since you're still developing on studio 6, I can only assume you're still using the original installed version of MFC). If you'd like the dialog to look the other way, you need to upgrade your MFC version or upgrade your project to a newer version of studio (which comes with the newer MFC versions).

I have found a trick, a best solution making it possible, here it is:

// TODO: Add your control notification handler code here
CFileDialog dlgFile(TRUE, _T("png"), NULL, OFN_HIDEREADONLY | OFN_FILEMUSTEXIST | OFN_EXPLORER, _T("PNG files (*.png)|*.png|All files (*)|*||"), this);

// Check to see if this is Windows 2000 or later, if so use the
// Windows 2000 version of OPENFILENAME.
if (sizeof(OPENFILENAME) < 88)
{
	OSVERSIONINFO osvi;
	// zero memory and set struct size.
	::ZeroMemory(&osvi, sizeof(OSVERSIONINFO));
	
	osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
	
	// get the Windows OS version information.
	::GetVersionEx(&osvi);
	
	if (osvi.dwPlatformId >= VER_PLATFORM_WIN32_NT && osvi.dwMajorVersion >= 5 && dlgFile.m_ofn.lStructSize < 88)
	{
		// Windows 2000 version of OPENFILENAME has three extra members,
		// this was copied from newer version of commdlg.h...
		struct OPENFILENAMEEX
		{
			void* pvReserved; // 4 bytes
			DWORD dwReserved; // 4 bytes
			DWORD FlagsEx;    // 4 bytes
		};
		
		dlgFile.m_ofn.lStructSize += sizeof(OPENFILENAMEEX); // should equal an additional 12 bytes;
	}
}

if (dlgFile.DoModal() == IDCANCEL)
	return;