Brochure mode signature size

Hey, so you know the brochure printing mode? It normally prints a single
signature - one stack of pages, where if you fold the stack down the
middle, it forms a book. BUT, folding a stack of like 200 pages doesn't
really work too well. I'd be preferable to specify a signature size - e.g.,
single sheets of paper, each of which you fold down the middle and stack. I
thought I found where the code for that lies -
sd/source/ui/view/DocumentRenderer.cxx , PrepareBooklet(), at the end of
the function. But 1. the behavior I'd expect from that code doesn't quite
match what I see in the preview in the Print window, and 2. after I changed
the code to do what I wanted, and recompiled, the Print window behavior was
entirely unchanged. Does anybody know where the relevant code actually is,
or what's going on here?