class Main
{
  BackgroundWorker worker = new BackgroundWorker();
  Working_Hard wh_ref;

  worker_DoWork()
  {
    Working_Hard wh = new Working_Hard()
    wh_ref = wh;
    wh.starte_timer();
  }

  button1_click()
  {
    worker.RunWorkerAsync();
  }

  button2_click()
  {
    wh_ref.verändere_parameter(parameter);
  }
}

class Working_Hard
{
  MMTimer timer = new MMTimer();

  starte_timer()
  {
    timer.Start();
  }

  timer_Tick()
  {
    //mache was zeitkritisches ...
  }

  verändere_parameter(parameter)
  {
    //Parameter ändern, die im Tick-Event verarbeitet werden ...
  }
}

class Program {
	private WorkingHard _wh;
	
	private void startWork() {
		_wh = new WorkingHard();
		_wh.Start();
		_wh.StatusUpdate += (o,e) => this.Invoke(new Action<object, WorkingHardEventArgs>(wh_StatusUpdate), o, e);
	}
	
	private void updateParameters(Foo bar) {
		_wh.updateParameter(bar);
	}
	
	private void wh_StatusUpdate(object sender, WorkingHardEventArgs e) {
		this.progressBar.Value = e.Percentage;
	}
}

class WorkingHard {
	MMTimer _timer = new MMTimer();
	
	public void Start() {
		_timer.Start();
	}
	
	private void Tick() {
		//Do something

		OnStatusUpdate(42);
	}
	
	private void OnStatusUpdate(int percentage) {
		if(StatusUpdate != null) StatusUpdate(percentage);
	}
	
	public event EventHandler<WorkingHardEventArgs> StatusUpdate;
}

class WorkingHardEventArgs : EventArgs {
	public WorkingHardEventArgs(int percentage) { 
		_percentage = percentage;
	}
	
	private int _percentage = 0;
	public int Percentage { get { return _percentage; } }
}

ThreadPool.QueueUserWorkItem(o => _timer.Start());