The custom layout also rotates each Node according to the actual angle at which the node was positioned. This information is available on the CircularVertex used by the LayoutNetwork that the CircularLayout constructs from the nodes and links of the diagram. Furthermore, when laying out the nodes it also flips the angle of the TextBlock so that the text is not upside-down.
GraphObject.mouseEnter and GraphObject.mouseLeave event handlers on the Node template highlight both the Node and all of the Links that connect with the Node. The same event handlers on the Links highlight that Link and both connected Nodes. Changes made in these event handlers automatically are not recorded in the UndoManager, although this sample does not enable the UndoManager anyway.