Version:           0.10.2 (using 4.4.2 (KDE 4.4.2), Kubuntu packages)
Compiler:          cc
OS:                Linux (x86_64) release 2.6.32-22-generic

When opening a document in Okular with the scaling set to "fit to width" then if the window size is such that the height of the document needs a vertical scrollbar when the scrollbar is absent, but does not need it when the scrollbar is present, then the scrollbar flickers on and off continuously.

Easy way to reproduce it:
Open a landscape mode EPS (probably works with other formats as well) file with Okular.
Slowly resize the window vertically until the vertical size is just too small to show the whole page without a scrollbar
The scrollbar will then appear and disappear in an endless cycle until you resize the window again (larger or smaller).