Album layout, why can't I scroll with the arrow keys?

After the recent changes I find myself unable to scroll through images quickly by using the arrow keys. Before the changes this was not a problem.

By this I mean, right and left arrow to jump to the next image in the line without having to scroll.

For instance, this album: http://imgur.com/a/twSo9#iM2ls

Using Firefox 7 on Linux.