Nope, it does not help after editing.

$ postproc.py its2D.vtk
********************************************************************************

WARNING: Imported VTK version (5.8) does not match the one used
         to build the TVTK classes (5.6). This may cause problems.
         Please rebuild TVTK.
********************************************************************************


Traceback (most recent call last):
  File "./postproc.py", line 8, in <module>
    from sfepy.postprocess import Viewer, get_data_ranges, create_file_source
  File "c:\sfepy\sfepy\postprocess\__init__.py", line 1, in <module>
    from viewer import Viewer, ViewerGUI
  File "c:\sfepy\sfepy\postprocess\viewer.py", line 33, in <module>
    from sfepy.postprocess.utils import mlab
  File "c:\sfepy\sfepy\postprocess\utils.py", line 15, in <module>
    Source = mayavi.core.source.Source
AttributeError: 'module' object has no attribute 'source'