placement of redbox popups

Hi, I've got Redbox working -- very cool -- but I can't find anything
in any documentation that says how to control where the popup is
placed. As of now, it is placed at the top of the page -- but my page
scrolls down considerably, and if I scroll down, then pop up a redbox,
it's up at the top of the page, out of sight.

Any ideas?

Charlie