Window shrinks to vertical strip when resized in 3d mode

On ubuntu 12.04, any change in the size of Scratch's window causes it to turn black and slowly shrink down to a thin strip, where it remains, unresponsive. Quite an interesting bug!

Here's a video:
http://youtu.be/bpTX7O3NDy4

Window resize events work fine when I am logged in in "2D" mode, so this is somehow related to Ubuntu's 3d mode. It's not clear if the cause of this problem resides in the squeakvm, which Scratch runs on, or the Scratch binary.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: scratch 1.4.0.6~dfsg1-2~ubuntu12.04.1
ProcVersionSignature: Ubuntu 3.2.0-27.43-generic 3.2.21
Uname: Linux 3.2.0-27-generic x86_64
ApportVersion: 2.0.1-0ubuntu11
Architecture: amd64
Date: Tue Jul 24 13:40:56 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: scratch
UpgradeStatus: No upgrade log present (probably fresh install)