The LitIconicNode example class inherits from GoIconicNode and just adds a HighlightColor property that specifies the color drawn behind the Icon. The example class has the HighlightColor set to Color.Red when the mouse passes over the node, and set back to Color.Empty when the mouse leaves the node. (The mouse was over “Lit 2” when the screen shot was taken.)
This screen shot also displays a GradientColorLink.