Settings window too big if there's an error message in a plugin

[Ricardo Graça]

If, for some reason, there's an error message in one of the plugins, the settings window is expanded so that the whole message string is visible. I attached two pictures showing this problem. You can see that the problem is in the plugins tab. The error message seems to be in the Youtube plugin (? Hard to tell as it's just a green arrow). This probably requires some special conditions so it may not be all that easy to reproduce.
I have a portuguese (from Portugal) Google Apps account that I have entered in the Online Accounts dialog window (through Empathy). In Portugal the youtube service isn't available to users of Google Apps yet, so that's what the error message is saying. I usually see that message in the web browser if I try to login to youtube with my Google Apps account.

Steps to reproduce:

1) Have a Google Apps account in a country that doesn't support youtube service yet
2) Open Shotwell
3) Go to menu Edit -> Settings

Expected results:
The settings window isn't stretched beyond the screen's boundaries

Actual results:
The settings window is expanded horizontally beyond the screen's boundaries so that an error message is visible in the plugins tab

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: shotwell 0.12.3-0ubuntu0.1
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: Wed Jul 25 23:18:50 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
ProcEnviron:
 LANGUAGE=pt:pt_BR:en
 TERM=xterm
 PATH=(custom, user)
 LANG=pt_PT.UTF-8
 SHELL=/bin/bash
SourcePackage: shotwell
UpgradeStatus: No upgrade log present (probably fresh install)