Tests fail with GTK+ 3.5

Several of the gtk tests are failing with the following error on Quantal now, with GTK+ 3.5:

Traceback (most recent call last):
  File "/tmp/buildd/ubuntu-sso-client-3.99.0/ubuntu_sso/gtk/tests/test_gui.py", line 882, in test_on_captcha_generation_error
    gui.CAPTCHA_LOAD_ERROR)
  File "/tmp/buildd/ubuntu-sso-client-3.99.0/ubuntu_sso/gtk/tests/test_gui.py", line 451, in assert_correct_label_warning
    self.assert_color_equal(expected, actual)
  File "/tmp/buildd/ubuntu-sso-client-3.99.0/ubuntu_sso/gtk/tests/test_gui.py", line 182, in assert_color_equal
    self.assertEqual(rgba_color, tmp, msg % (rgba_color, tmp))
  File "/usr/lib/python2.7/dist-packages/twisted/trial/unittest.py", line 270, in assertEqual
    % (msg, pformat(first), pformat(second)))
twisted.trial.unittest.FailTest: Text color must be <Gdk.Color(red=1.000000, green=0.000000, blue=0.000000, alpha=1.000000)> (got <Gdk.Color(red=0.000000, green=0.000000, blue=0.000000, alpha=1.000000)> instead).
not equal:
a = <Gdk.Color(red=1.000000, green=0.000000, blue=0.000000, alpha=1.000000)>
b = <Gdk.Color(red=0.000000, green=0.000000, blue=0.000000, alpha=1.000000)>

This is due to a performance improvement change in GTK+ where the style update doesn't occur until the widget is actually drawn, and so the color we get from the style doesn't match the one we set.