>Write one program that launches the conversion program. The conversion program runs invisibly. The conversion program outputs a time-stamp or other marker into a disk file every N iterations. The launcher program looks for updates to the marker / time-stamp and updates a screen output to notify the user what the status is. The marker can be the conversion progress % or just a time-stamp which shows the last time the conversion program updated it.

IOW (just like Craig's suggestion to resort to threading), I'm serving the OS, or have to invent tricks to avoid the customs/tax/excise that the OS levies on the app.

Wasn't the purpose of the OS to be the environment in which the apps would run? Wasn't the basic idea why the computers were invented the data processing?

O, tempora...

Writing anything special is not worth the while. A conversion is basically one long prg which is run once or several times, and it's run by me. During test runs (as there will always be errors - misspelled fields mostly, then misunderstood fields) I have to be able, always was, to simply "do convert" from a command window (not necessarily The command window, any simulation also works fine) and check the results when it ends.

Googling this I've found that having a form is something that may pass the muster - so I'll try to employ a thermometer. We'll see.