Have the ability to zoom and have a part of the screen be the outside of the document, so that you could rest your hand, whilst editing the edge of the document.

E. g. the second screenshot is from a table I was filling out and when I got to the rightmost column I couldn't write in it as easily as in the other ones. I am right-handed, so in those screenshots the area is on the right side of the page, but this should work for left-handed people as well, if the area was on the left-hand side of the document.