Dave is correct. You cannot execute prontoscript on a button that you do not physically press on the screen (using links in PEPv1).

Also, ProntoScript is not "shared" between activities. That is, when you leave one activity to go to another and the return to previous, any state of previous activity is lost and it restarts from scratch unless you somehow save/restore state using System.setGlobal()/getGlobal().

If you need your screen control and some other script active concurrently and don't want to do what I suggest above, you need to "merge" 2 activities moving pages, copying/merging activity script as needed to make a single activity that contains pages from both of your original activities.