private void loadXML(ref TestGraph1 tg1)
{
XmlSerializationContext xmlsc = new XmlSerializationContext();
xmlsc.Load(System.Environment.GetEnvironmentVariable("TEMP") + "\\TestGraphPersistence.xml");
xmlsc.ContextEntities.Add("Model", new Model("Reconstituted Model"));
tg1 = (TestGraph1)xmlsc.LoadObject("TG");
}