From today's meeting, superseeds #345, #182, #100. Much of the ideas from those issues either belong in examples or a neuro-widget library @clewis7

1. I think we will keep a very simple event system in fastplotlib. I will explore observ and see whether it makes sense to incorporate it within fastplotlib or not. Otherwise we will make a very simple event system in fastplotlib and give users examples of how to use observ or other libs for more complex event handling
2. Using what Almar and Korijn call a store model is probably a better paradigm than circular events when those types of interactions are required. Have a concept of a "state", for example "selected cell" and events modify that state. This way you don't have to worry about circular events. For example, if you click on a cell it modifies "selected cell", if you click on a temporal component it modifies "selected cell" etc.
3. Pull out the Interaction class from fastplotlib and put it into a new neurowidgets that Caitlin will work on.

Proposed basic API for adding event handlers suggested by Almar:

graphic.add_event_handler("feature", callable)

# could also be a pygfx event and use the same API?
graphic.add_event_handler("click", callable)