Here's an example thrown together in a couple of minutes.
An event callback is created for the "mouse Enter" event of an FP control.
It is fed a queue reference. The VI simply takes the event data, adds the current control value and sends it via Queue.
The Queue has data in it whenever the mouse enters the bounds of the FP control. The Event structure is not actually involved.
I have an event structure included only to allow for the "stop" button functionality. It can be implemented without.