Can a script be written that would allow a user to go to the previous screen they were looking at, even if the previous screen is in a different file? I've written a program where upwards of 20 files could be open at the same time. As it is now, the user has to click buttons or tabs to go back or forward. It would be neat if they could just click a button to return to the previous screen.

Yes, but it would require scripting every layout change not involving a report and not allowing access to the layout menu in any of your files. You would use a preferences file that contains globals holding the current file name and layout number. And you would need a script to return to each file, based on what the global filename field contained, which would call a script to Go to Layout [based on global layout number field].