Testcase at http://developer.gnome.org/projects/gup/hig/2.0/hig-2.0.pdf

Steps:
0) Load testcase in evince
1) set zoom to 100% and resize window so that it's not as tall as one page in the document
2) Press PgDown 2 or 3 times

Expected results:
Each time PgDown is pressed, the page is scrolled down by the same amount (window height)

Actual results:
The first PgDown does that, but the next PgDown only scrolls a little so that the beginning of the page is aligned at the top of the window (depending on window height, this happens on 2nd or 3rd PgDown). You can see that the display flickers, as if it first actually scrolled down further and then snapped back.

Evince + poppler HEAD.