oops, sorry; finding this UI a little odd. my UV editor grid is very small (few cells in the grid) and not square -- cells are oblong.
http://i.imgur.com/Du1KhBK.png
I wonder if this has something to do with my inability to get any cube, even one cube face, to unwrap into the editor. I have no idea why my UV grid doesn't look like the ones in all the tutorials and examples (which are square in aspect ratio and have a lot more cells).