protected ConnectorViewModel(ElementViewModel element, string name, Color color)
 {
     _element = element;
     _name = name;
     _color = color;
 }
 public OutputConnectorViewModel(ElementViewModel element, string name, Color color, Func<BitmapSource> valueCallback)
     : base(element, name, color)
 {
     _connections = new BindableCollection<ConnectionViewModel>();
     _valueCallback = valueCallback;
 }