Thanks so much
...for your different solutions, all of which are expanding my understanding of how to program switches and triggers in Isadora. Using the Trigger Value actor as a binary 'on/off' switch is powerful. Monty talks about this too. In the end I went for a mouse watcher with no modifier triggering a zero/off, so that i can toggle between on and off using the modifier i set for the first Mouse Watcher (img). This is good, but following the tutorial advice, I am now playing with the Stage Mouse Watcher to get something closer to the kind of 'touch = 'on' / release = off' experience.