I did not continue the project after I started refactoring. The reason is that the code is getting much more complex than the previous version (basically 3 classes and 1 helper class). And since there did not seem to be much interest, I did cooler things first.
I will finish the upcoming version if I need the code myself, this can take a while.
I have uploaded the last working version before I started refactoring (built with vs2010, qt4.7.2): current release can always be found here:
Note that the upcoming version will be different, with a bloat of classes. Because I want to be able to use QWidges and QGraphicsItems the inheritance tree of QT forces me to separate things into many different classes. This previous version is not cleaned up, some messy code, but it works well.
Note: Look at ExampleApp, the example nodes are defined in mainwindow.h! Check that to see how it works.
However, you maybe have to adapt the build process. I did a quick test build with qmake and nmake on command line, seems to work. In VS2010 the includes in debug seem messed up (that version is one commit after restructuring dirs). The new version will use CMake.