canvas F5 execute does nothing after module mod with configure VTK object

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Play with streamtracer.
2. Configure vtkStreamTracer object, change something, click apply.
3. Press F5 on canvas.

What is the expected output? What do you see instead?
Expect network to be executed, including streamtracer.  

Instead, DeVIDE thinks that the module is not dirty and skips it.  However,
if I click on the execute button of that module's config window, it does
execute.

Original issue reported on code.google.com by cpbotha on 27 Jul 2009 at 5:13