I was very close yesterday, just a matter of deciphering the proper syntax for specific items in the display control which are frustratingly not documented except in code in a buried example in the install tree. Display Active layer only would be "Option.AcitveLayerOnly"
MGCPCB.View pcbView = ExpDoc.ActiveViewEx; MGCPCB.DisplayControl dsc = pcbView.DisplayControl; if (dsc.get_Option("Option.Netlines.Enable") == MGCPCB.EPcbGraphicsItemState.epcbGraphicsItemStateOffEnabled) { dsc.set_Option("Option.Netlines.Enable", MGCPCB.EPcbGraphicsItemState.epcbGraphicsItemStateOnEnabled); } else { dsc.set_Option("Option.Netlines.Enable", MGCPCB.EPcbGraphicsItemState.epcbGraphicsItemStateOffEnabled); }