Background/grid is so faint as to be invisible when using "ambient" screen

I can't actually play gnome Sudoku on my pc since upgrading to oneiric, because the lack of visible grid makes it too difficult to see the relationships between the figures. Could we at least have an option to make the grid/background darker, please?

Thanks.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: gnome-sudoku 1:3.2.0-0ubuntu1
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic x86_64
ApportVersion: 1.23-0ubuntu3
Architecture: amd64
Date: Wed Oct 19 11:55:27 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
ProcEnviron:
 LANGUAGE=en_GB:en
 PATH=(custom, no user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-games
UpgradeStatus: Upgraded to oneiric on 2011-10-15 (3 days ago)