Add Notifications for tooltip events

[stargazing-dino]

I imagine this would be useful to see when a tooltip is on the screen and where. Top level UI might find something to do with this information.

I saw a neat answer from Remi on Notifications. This is a separate from a controller.

https://stackoverflow.com/a/51460832/8213910

We would add notifaction listener and possibly provide:

• target postion and sizing
• tooltip direction and sizing
• visible, hidden
• more possibly

[stargazing-dino]

class TooltipNotification extends Notification

call tooltipNotification.dispatch().