Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/gtk/viz/branchwin.py", line 453, in _tree_revision_activated
    self.show_diff(revision.revision_id, parent_id)
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/gtk/viz/branchwin.py", line 619, in show_diff
    window.set_diff(description, rev_tree, parent_tree)
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/gtk/diff.py", line 519, in set_diff
    self.diff.set_diff(rev_tree, parent_tree)
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/gtk/diff.py", line 334, in set_diff
    self.diff_view = DiffView()
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/gtk/diff.py", line 248, in __init__
    DiffFileView.__init__(self)
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/gtk/diff.py", line 70, in __init__
    self.construct()
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/gtk/diff.py", line 84, in construct
    self.apply_gedit_colors(self.buffer)
  File "/usr/lib/python2.6/dist-packages/bzrlib/plugins/gtk/diff.py", line 114, in apply_gedit_colors
    buf.set_style_scheme(style_scheme)
TypeError: GtkSourceView.Buffer.set_style_scheme() argument 1 must be gtksourceview2.StyleScheme, not None