I made the above comment from an alternate universe where `addEventHandler` kept weak references to the objects it received. Ultimately, I decided I preferred *this* universe, though, so you can ignore this. Sorry for the confusion :P

One nice thing about `addEventListener` is that, when given an object, it will call the `handleEvent` in the context of that object. This would save you from having to create a bound copy of each instance's `refresh` method, but that optimization isn't worth blocking on.