There is also the click even. For clicks, we are stopping propagation, and produce one call, with the list of all impacted annotations. So even if we could solve mouse over/out differently, we need to retain the current behavior for clicks.

I have a different idea: we could use the event.data field to pass a `getAnnotations()` function reference (when the handler is bound), so the receiver can call event.data.getAnnotations() when the list of annotations is needed.