Since upgrading to the 3.x series of evince, the thumbnails in the
sidebar now have huge margins surrounding them, which get included in
the region highlighted when clicking on a page thumbnail.  The margins
on each side of a page thumbnail take up more than half the width of a
page each.  In previous versions of evince, the sidebar had much more
reasonable margins, which made it possible to shrink the sidebar to just
over the width of one page thumbnail.

I've attached a screenshot.

- Josh Triplett