Thanks for the comments!
I understand that you wrote everything yourself, or do you make use of other third-party libraries besides CEGUI?
I think I should include a separate page mentioning the third party libraries that are being used. The 3rd party libs can be found in the dependencies directory.
http://svn.sourceforge.net/viewvc/cadabra/trunk/All except that and the Solid collision detection library (used by the Solid add-on) has been written by me so far. I would really appreciate if someone tried to port it to linux, took control of the OpenGL plugin, or even developed a new scenegraph plugin. There is a lot of cool programming to be done.
About the screenshot: it looks like you can preview your models like they would look ingame, lighting wise? That looks really helpfull, because there can be a big difference between a view in a modeler and the actual view in game.
Yes, this is exactly the point of the model viewer. With it you can control all the lighting variables and view the models just like they will look in game. There is a quicklaunch button in the max exporter that will preview the model in cadabra with only one click. Also, the shader parameters are exported from max and are built into the model files.