Hi, to change the stroke style of a single node when selected you can subscribe to the NodeSelected (change the stroke style there) and NodeDeselected (restore the stroke style there) events of the drawing view's event sink service. Note that you should also change the selected appearance change mode of the view, so that it does not change the stroke style of the selected node:
view.InteractiveAppearance.SelectedAppearanceChangeMode =
AppearanceChangeMode.None;