public override void onMetronomeEvent(object sender, metronomeEventArgs e) { // InvokeRequired required compares the thread ID of the // calling thread to the thread ID of the creating thread. // If these threads are different, it returns true. if (this.spinBox.InvokeRequired) { FormControlDelegate updateControl = new FormControlDelegate(increaseSpinBox); spinBox.Invoke(updateControl, new object[] { e }); } else { increaseSpinBox(e); } }