public void addSignal()
{
SignalComponent priorSignal = null;
SignalComponent signal = new SignalComponent( this );
if( signalComponents.Count > 0 )
priorSignal = signalComponents.Last();
signalComponents.Add(signal);
signal.Location = new Point(10, 10);
if( priorSignal != null )
signalConnectors.Add( new SignalConnector( ref priorSignal, ref signal ) );
Invalidate();
Update();
}