horizontal thumb leaves window droppings on vertical scroll

When fully zoomed (1:1), the scrollbar thumbs leave window droppings. For example, scrolling vertically produces images of the horizontal scrollbar. I suspect this is due to ubuntu's (compiz's?) fancy new thumbs, which slightly invade the content area, and the ufraw code thinking it owns the entire content rectangle.

A screenshot is attached.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: ufraw 0.18-1.1
ProcVersionSignature: Ubuntu 3.0.0-17.30-generic 3.0.22
Uname: Linux 3.0.0-17-generic x86_64
ApportVersion: 1.23-0ubuntu4
Architecture: amd64
Date: Wed Apr 18 20:42:04 2012
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release amd64 (20100429)
ProcEnviron:
 PATH=(custom, user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: ufraw
UpgradeStatus: Upgraded to oneiric on 2012-01-09 (100 days ago)