IMPLEMENT_CLASS(wxPreviewFrame, wxFrame)

BEGIN_EVENT_TABLE(wxPreviewFrame, wxFrame)
    EVT_CLOSE(wxPreviewFrame::OnCloseWindow)
END_EVENT_TABLE()

...
void wxPreviewFrame::OnCloseWindow(wxCloseEvent& WXUNUSED(event))
{
    if (m_windowDisabler)
        delete m_windowDisabler;

    // Need to delete the printout and the print preview
    wxPrintout *printout = m_printPreview->GetPrintout();
    if (printout)
    {
        delete printout;
        m_printPreview->SetPrintout(NULL);
        m_printPreview->SetCanvas(NULL);
        m_printPreview->SetFrame(NULL);
    }
    delete m_printPreview;

    Destroy();
}