Move events not delivered when mouse is held down and subscriptions change based on mouse button state

[hoelzro]

Sorry for the strange issue title - I don't know of a better way to describe this. Here's some example code:

https://gist.github.com/hoelzro/7ec33aaf951cdc5e86eaa9683926fc66

In short, subscriptions is set to [ups, moves] if the mouse is down, and [downs] otherwise. With this configuration, move events don't end up getting delivered to the update function. If you change the isDown == true branch to be [ups, downs, moves], move events are delivered.