I am trying to work in IDL to identify an event when the mouse pointer is hovered over a node in a displayed nodes-and-edges graph in a GUI. In my program, I use a virtual trackball 'myBall' to track the mouse motions and the events resulting from mouse actions. Can you please help identify a hover event with this implementation? Can it be implemented using widget control instead?
So far I have tried implementing this using an event_handler, but it does not work with my program.