Feature request: callbacks for lifecycle events #82
Description
When I show a tooltip, I start up a background refresh task that needs to be cancelled when the tooltip disappears. I can't see any events in the OT docs to help with that situation (and maybe I'm missing something).
If that doesn't exist, I'd suggest at least 'on show' and 'on hide' event callbacks? Ideally this would use (e.g.) jQuery's event management but that would be a significant job given the various backend adapters that would need to be implemented. So perhaps a single callback function could be registered instead.