Thanks for all those who responded to my question. In this case, I was having trouble using Studio with the nested activities because the filename isn’t known until runtime. The solution, which was hinted at by Anil_G, was to forego opening notepad entirely, and simply write what I wanted to write to a text file directly using the “Write Text File” activitiy. It is much faster, and overwrites what’s there, which is what I wanted. I’m not sure this solution would work with other applications, but since notepad is very simple, it works here.