bool MyApp::OnInit()
{
    const wxString szName = wxString::Format( "MyApp-%s", wxGetUserId().c_str());
    m_checker = new wxSingleInstanceChecker( szName);
    if ( m_checker->IsAnotherRunning() )
    {
        wxLogError( _( "Another program instance is already running, aborting."));
        return false;
    }

    // ... more initializations ...

    return true;
}

int MyApp::OnExit()
{
    delete m_checker;

    return 0;
}