Unable to Scroll in Change Brush Menu

[Michael Murphy]

I'm using a Wacom Intuos tablet with MyPaint, and when select the change brush menu from the toolbar, the menu will not scroll at all. However, if I select the Change Brush menu from the menubar (B), it works fine.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: mypaint 1.1.0-3
ProcVersionSignature: Ubuntu 3.19.0-15.15-generic 3.19.3
Uname: Linux 3.19.0-15-generic x86_64
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
Date: Mon May 4 09:19:14 2015
InstallationDate: Installed on 2015-04-21 (12 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Beta amd64 (20150326)
ProcEnviron:
 LANGUAGE=en_US
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: mypaint
UpgradeStatus: No upgrade log present (probably fresh install)