Hiding an MFC dialog box without taskbar / flickering etc

How to: Hiding an MFC dialog box without taskbar / flickering etc

If you show your dialog using CDialog::DoModal() the framework will make sure your dialog is shown. There is only one way to prevent a modal dialog from being shown:

In your MFC Project dialog e.g. CHiddenDialog.cpp

BEGIN_MESSAGE_MAP(CHiddenDialog, CDialog)
    ON_WM_WINDOWPOSCHANGING()
END_MESSAGE_MAP()

BOOL CHiddenDialog::OnInitDialog()
{
    CDialog::OnInitDialog();
    m_visible = FALSE;

    return TRUE;
}

void CHiddenDialog::OnWindowPosChanging(WINDOWPOS FAR* lpwndpos) 
{
    if (!m_visible)
        lpwndpos->flags &= ~SWP_SHOWWINDOW;

    CDialog::OnWindowPosChanging(lpwndpos);
}

in your header file CHiddenDialog.h

void OnWindowPosChanging(WINDOWPOS FAR* lpwndpos);