Perhaps see if you can get in the NeosisGUI beta. It looks very interesting: http://www.noesisengine.com/noesis_gui_features.htm You write the GUI in XAML, and the rest of the API is C++. It's all 3D, and is built on top of OpenGL and DirectX. It looks mega fast. For rapid prototyping, perhaps consider Processing. It is essentially Java, with some nice APIs, and a rendering context already setup for you.