MFC, invisible dialog app with timer

[BertAndErnie]

Hello

I'm making a MFC program that needs to start invisible, with a timer running. Then on timer expiry, if certain conditions are met, a dialog is supposed to display. I am trying a Dialog based application because that seems the most straightforward. I have been able to get roughly what I want with the standard modal dialog code generated by Visual Studio, by putting ShowWindow(SW_HIDE) in the dialog's OnPaint method. That approach causes a flicker of the dialog when the program is starting and I think there is a more correct way.

I have also tried:

BOOL CMyApp::InitInstance()
{
    InitCommonControls();
    CWinApp::InitInstance();
    m_pMainWnd = new CMyDlg;
    UINT_PTR uTimerId = SetTimer(NULL, 0, 2000, &TimerCallback);
    return (m_pMainWnd != NULL);
}

But this causes an assertion failure in CDialog at

BOOL CDialog::PreTranslateMessage(MSG* pMsg)
{
	// for modeless processing (or modal)
	ASSERT(m_hWnd != NULL);
}

It makes sense that m_hWnd is NULL because I haven't called the dailog's DoModal method but I don't know what to do about it.

What is the correct technique for this kind of application?

Thanks.