The website of that software states:
If Ms-Windows cuts off your window to maximum screen size and you miss a scrollbar use the 'Oversize'-Tab
to set the window size to your needs.
Though note that it also says that the tool is written in Perl (a rather unusual choice?), it extends the Windows desktop beyond its physical bounds, and that there exists no maximum virtual screen resolution.
"No limit, as large as you like" is a rather bold claim, as there are several very obvious hard limits both from the hardware and from Windows.
