Had a nice chat with Jerry at PGM. He tells me that when you swipe some bars to copy, EVEN if you do not see the part marker highlighted, it comes with the copied bars. Then when you paste, BIAB assumes you want a new part and thus starts the "new" part on a new line, thus the added gray area.

If you don't want that (my goal) one has to click on the new part marker TWICE (turning it from blue to green to clear) to get the old formatting of 4 bars to a row back.

It turns out that this part marker coming along with highlighted bars 1 and 2 (even though there is no visual indication that you are bringing along the part marker) is only a behavior that involves bar #1.

So you have a choice.

Swipe bars 1 and 2 that you want to repeat and then go through the process of turning off the automatically, but unwanted new part and returning to the default 4 bars per line format

OR

Don't do any copying from bar #1 and avoid this whole automatic make a new part assumption that BIAB makes.

I have submitted a suggestion the PGM that they make this copy/paste function show whether the part marker has been selected so that the user has a choice of what he/she is actually copying. This will bring the program into alignment with standard copy and paste functionality that all computers use.