private void bgWorker_Play_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker bw = sender as BackgroundWorker;
PlayOpts opts = (PlayOpts)e.Argument;
MusicNoteLib.PlayMusicStringWithOptsCB(opts.strNotes, opts.nMidiOutPort, opts.nTimerRes,
new MusicNoteLib.ParserTraceDelegate(OnParseTrace),
new MusicNoteLib.ParserErrorDelegate(OnParseError), IntPtr.Zero);
}