Feedback M should mute when the curves are selected

currently the track header or track must be selected, but a lot of work is done in the curve section so focus on that should register M as well
that had me scratch my head for a bit

 

come to think of it, i think it's a bug in focus registration: when you click on a curve section and you had another track selected, it doesn't select the track that the curve are on... like so