/// <summary>
/// stops listening.
/// </summary>
private void removeHook() {
DLLImports.UnhookWinEvent(m_hhook);
m_hhook = IntPtr.Zero;
dele = null;
}
/// <summary>
/// start listening
/// </summary>
private void enableHook() {
dele = new DLLImports.WinEventDelegate(WinEventProc);
m_hhook = DLLImports.SetWinEventHook(EVENT_SYSTEM_FOREGROUND, EVENT_SYSTEM_FOREGROUND, IntPtr.Zero, dele, 0, 0, WINEVENT_OUTOFCONTEXT);
}