To make sure you know how to search versions in the history tree of Vistrails do the following simple task:
1) In the History view locate the version tagged "EX1". Execute this version and annotate it with the name that appears in the visualization.
2) Query by Example Delaunay
From the root version on the History View design a pipeline to reproduce the following image (obs. The colors are important).
1) From the root version on the History View design a Vistrails pipeline equivalent to the VTK pipeline equivalent to the code
translate the C++ VTK source code into a Vistrails/VTK pipeline
2) locate the only version in the file that has a module X connected to a module Y.
Note that there are many versions in the vistrail. You should use the