//subscription mechanism
public void CustomizedSubscribe(MappingUpdateSubscriber <T> aSubscription)
{
subscription = aSubscription;
subscription.AttachTo(this);
}
public void Subscribe(Control aSubject, bool aAllowNulls, ListControlMapping aListMapping)
{
subscription = new MappingUpdateSubscriber <T>(this, aSubject, aAllowNulls, aListMapping);
}