So all I need is the following program, instead of IMGTOOL?
http://www.andante.org/mkisofs.html
Can I assume that the following scenario is the proper big picture of the flow you have detailed?
After some user interaction to select a LB, PGCEDIT modifies the specific IFO file, for the VOB set that contains the LB. Then, calls MKISOFS.EXE in which it takes the IFO, BUP, and VOB files and creates an ISO image. Finally, PGCEDIT calls IMGBURN, without giving you the MDS file. But you scan the ISO file and locate the LB flag inside the IFO file and burn the DVD.
As a suggestion, if the last sentence is true, it would be nice if PGCEDIT were to give you information that would negate the necessity to search for the LB, FWIW!
Thanks,
GParent
P.S.
You have started a quest for me to learn more about Layer Break and what DVD Players do with or without them.