'whitesmoke', stroke: 'lightgray' }),
          // define a horizontal Panel to place the node's text alongside the buttons
          new go.Panel('Horizontal')
            .add(
              new go.TextBlock({ font: '30px Roboto, sans-serif', margin: 5 }).bind('text', 'key'),
              // define a vertical panel to place the node's two buttons one above the other
              new go.Panel('Vertical', { defaultStretch: go.Stretch.Fill, margin: 3 })
                .add(
                  go.GraphObjec