All the standard Mach3 screens, and as far as I know, all the wizards (except for the latest one Ron did) are set out in such a way as to leave the bottom of the screen empty; leaving space for the standard windows task bar.
I think this is a good principal to follow especially if doing screens for others to use.
Again IMO there are valid reasons to shy away from auto screen enlarge. I don't expect others to share that opinion.

Greg