pyglet + pyglet_gui + x?

exploring python3, type hints, found pyglet pyglet_gui proposing a more declarative, modular approach to draw components/controls and separating theming from structure .
it ignited my imagination, what if you could use a simple one way data-binding? ui observing changes, triggering back signals-like to models/view-models ? I played with a naive, gist like, mvvmish ... sort of implementation then simplistic xml parsing could allow, potentially type hinting with just the right schema? and eventually expand the declarative mechanics to ui composition ?

TODO: everything