Traits-capable windowing framework
The TraitsUI project contains a toolkit-independent GUI abstraction layer, which is used to support the "visualization" features of the Traits package. Thus, you can write model in terms of the Traits API and specify a GUI in terms of the primitives supplied by TraitsUI (views, items, editors, etc.), and let TraitsUI and your selected toolkit and back-end take care of the details of displaying them.
