Touchpad scrolling in Ubuntu Software Centre is broken

Summary:

Scrolling in Ubuntu Software Centre using the touchpad is broken - scrolling down (for example) causes the screen to judder and make no downward progress.

Steps to reproduce:

1) Enable two-finger scrolling (n.b. touchpad configuration is currently handled by "Pointing devices" - replacement for gsynaptics in the Software Centre).

2) Open Ubuntu Software Centre.

3) Attempt to two-finger scroll down the page - the screen simply judders (almost as if two source of scroll events are fighting to scroll in either direction).

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: software-center 13.10-0ubuntu4.1
ProcVersionSignature: Ubuntu 3.16.0-29.39-generic 3.16.7-ckt2
Uname: Linux 3.16.0-29-generic x86_64
ApportVersion: 2.14.7-0ubuntu8.1
Architecture: amd64
CurrentDesktop: XFCE
Date: Tue Jan 13 21:32:37 2015
ExecutablePath: /usr/share/software-center/software-center
InstallationDate: Installed on 2015-01-10 (3 days ago)
InstallationMedia: Xubuntu 14.10 "Utopic Unicorn" - Release amd64 (20141022.1)
InterpreterPath: /usr/bin/python2.7
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_GB:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: software-center
UpgradeStatus: No upgrade log present (probably fresh install)