What is the shortcut in eclipse to go half a page up and down?

Question

Basically, I want to move the scrollbar up and down with shortcuts instead using the up arrow.
I'm using Mac OS X.

Answer 1

Page up and page down should scroll up and down a page at a time for you. I don't think you can do half a page specifically.

Edited to add: This should scroll so that the upper or lowermost line on the page you scrolled from becomes the first or last line on the next page, which makes it easy to keep your place.