Node Shader Editor

I would like to code a simple node editor with C++ and QT 4.7. I am newbie in QT. Do you know some opensource app or example with QT using nodes. Can you give me some advices?

I want to do something similar like this:
http://www.dream.com.ua/p/shaderman7.gif

You may want to take a look at the diagram scene example to get you started with the graphical part.

HIH

Johannes