The dictionary containing the data associated with the receiver when it was created.
You can obtain this dictionary per event in each
mouseExited: method by querying the passed-in
NSEvent object with
[[event trackingArea] userData].
Getting Object Attributes
The options specified for the receiver.
The object owning the receiver, which is the recipient of mouse-tracking, mouse-movement, and cursor-update messages.
The rectangle defining the area encompassed by the receiver.