It's build on top of pyglet which is built around event-based programming, so it's already got the ability to do low-level callbacks from key/mouse events built

It's build on top of pyglet which is built around event-based programming, so it's already got the ability to do low-level callbacks from key/mouse events built in [1]. GUI widgets are a separate matter though and would probably require a separate library to do OpenGL GUI elements on top of this. [1] https://pyglet.readthedocs.org/en/pyglet-1.2-maintenance/programming_guide/mouse.html https://pyglet.readthedocs.org/en/pyglet-1.2-maintenance/pro...