Hi,
In case anyone should wonder...
On a 1024x768 screen, with mach at full screen, once you deduct the title and menu bars and the borders, I believe the area left for screen pages is 1016 x 719 pixels. ...that also happens to be the size the mach blue screens use for background images also (so I guess those guy already figured out this bit of trivia).
Curiously the mach standard 1024 screen set is 967x725 - I find that test screens at 725 high cut off the bottom few pixels when displayed in mach.
So, I'm going with 1016x719 as the magic size and will let "auto enlarge" handle physical screens other than 1024x768.
Dave