Edited:
I see only an unfortunate way how that works, Mike. With the _SCREEN visible.
Because the form has to be modal as you don't want a PRG that could have a READ EVENTS. The form can't be top level, or setting it modal does not work.
So you need to set the form to be in screen or in top level form and when you add a config with SCREEN=OFF or set _SCREEN.visible=.f. in your form code (load or init), then the form disappears.
I only see this working with another top level form or screen and since that's surely not what you want, you better have a main.prg as usual.
Chriss