After many fan requests I finally took a few hours to cook up a proof-of-concept showing how to construct a MVC decoupling between data storage, logic and presentation. The sample does not show:
- how to use the command pattern and how to implement undo-redo
- how to data-bind connections to shapes
- how to enable copy/paste
On the other hand, I did implement the (de)serialization of the diagram and shapes are templated. This simple bunch of code is the core architecture of how GraphSquare is internally (modulo the omissions I metioned above), all the rest is simply a few thousands hours of work more 
Note that this sample has been integrated into the DSK which contains a paradise of diagramming code if you wish to get started in WPF diagramming.
Thank you very much for your effort. I’m glad to have more details about the way your’re designing GraphSquare.
I’m looking forward to see a demo of GraphSquare !