I downloaded it and this is a lot clearer:
"Centered" acts like it did before. Whenever I type, it snaps to the center of the page and as I type it pushes text off the top of the page.
"Sticky" allows me to select anywhere on the page, that line becomes the line that acts as "centered" above. This is my ideal portrait working mode. I put the sticky line near the bottom of the page (so I can see if there's something after what II'm writing) and still feel like I'm working on a roll of typewriter paper.
"Off" just types down the page to the bottom and then text above scrolls up.
Great job, it seems like it's working now! Thanks for the quick updates.