Hi,
thanks Danny, but it doesn't quite work for me. Let me explain in detail what happens if I try what you suggest. If I autodetect a stop (either by right clicking on it and pressing autodetect, or by going to organ setting->stops/couplers etc. and then autodetect), I get a pop-up telling me to press the button I want to use. When I do, two previously greyed out options become available: toggle and send matching MIDI-output. I check both options. There are no options for lights at that point. I played around a bit in the stop/coupler etc. folder. I managed to get one button permanently lit. I have no idea how that happened; it is currently also operating two stops. It is lit no matter the state of the stops.