nding on the Shape.stroke to show selection
      itemTemplate:
        // each port is an "X" shape whose alignment spot and port ID are given by the item data
        new go.Panel()
          .bind('portId', 'id')
          .bind('alignment', 'spot', go.Spot.parse)
          .add(
            new go.Shape('XLine', {
              width: 6,
              height: 6,
              background: 'transparent',
              fill: null,
              stroke: 'gray'
            })
              .bind('figure', 'i