>I have a report that will group by categories picked by the user by using the evaluate(pcgroupexpr) in the report form's data grouping properties dialog, but can you programmatically set the "Group starts on" the "New line" or "New Page" so it can be a selection the user can choose prior to running the report.

The simplest idea that comes to mind is to have two copies of the report or, alternatively, create a temp report in run-time by copying the master copy and adjusting that in the report (once you figure out where is it set).

See also
Re: Start Group at New page dynamically Thread #991146 Message #1093902

(I also found my own message on this topic which was just a bit more detailed same idea).