thnx. That's one part of the puzzle solved
Documentation in default is way over my head. Do I understand correctly that Reaper uses a number of default terms (that's not the correct word, but ykwim) like ZOOM, bymarker and editloop?
And if I want the button also on the second page do I code that like this?
TRACK_MUTE t/1/mute t/2/mute ?