[vtkusers] upgrade vtk from vtk 5.0 to 5.8

[David E DeMarle]

> What I want to know is do we need to make code changes like these at every
> time we upgrade our vtk version?

It depends. Things change in every release, especially in major
releases (5.10->6.0).
vtkScalarBarWidget for example moved to a new class hierarchy when the
widgets were restructured to give them more capabilities.
Compare:
http://www.vtk.org/doc/release/5.0/html/a01987.html
and
http://www.vtk.org/doc/release/5.8/html/a01855.html
The bigger the version gap, the more likely it is that you will run
into incompatibilities.

We are getting better at documenting what the changes are to make
upgrading easier, but could stand improvement in this regard.
See:
http://www.vtk.org/Wiki/VTK#Summary_of_Changes

Back to the code:
Can you post .\vtk\vtkPBFEAView.cpp(313) and a few lines arounds it,
as well as the declaration of bar_actor_?