I have used selectionAdornmentTemplate to override the default rectangular one. But what am getting was double circle selection for a single node something similar to the attached image. Please find the code below.
this.$(go.Node, "Table", this.nodeStyle(),
{
selectionAdornmentTemplate: this.$(go.Adornment, "Auto",
this.$(go.Shape, "Ring",
{
fill: null,
stroke: "dodgerblue",
strokeWidth: 3,
}), this.$(go.Placeholder)
)
},
this.$(go.Panel, "Auto",
this.$(go.Picture, "image .svg",
{
desiredSize: new go.Size(60, 60),
imageStretch: go.GraphObject.Fill
})
),
this.makePort("T", go.Spot.Top, go.Spot.TopCenter, false, true),
this.makePort("B", go.Spot.Bottom, go.Spot.BottomCenter, true, false),
);