BIAB's scrolling behavior, both in the notation window and in the main window, is something about this program that I don't just find deficient or annoying, it angers me. It's jarring and it's difficult to work with. I avoid working with melodies at all because of the way the notation window behaves. It's pretty bad in the main window, too. Try clicking on bar 63 and dragging to bar 66 to copy those four bars.