private void unsubscribeFromEvents()
{
if (_switchWindowsScanner != null)
{
_switchWindowsScanner.FormClosing -= _form_FormClosing;
_switchWindowsScanner.EvtDone -= _form_EvtDone;
_switchWindowsScanner.EvtActivateWindow -= _switchWindowsScanner_EvtActivateWindow;
_switchWindowsScanner.EvtShowScanner -= switchWindows_EvtShowScanner;
}
}
}