[racket] Problem with on-subwindow-event

>> But I might be able to work-around by storing the mouse-event% when first processing, and then treat as duplicate all calls to on-subwindow-event that pass that same event.

I'm having trouble with this: Trying to store the mouse-event% with set! into a field at the first invocation and then checking against the mouse-event% passed in subsequent invocations using equal?, eq?, and object=? all fail to find and filter the duplicate calls. Does anyone have any ideas as to what I really should be using?

Kieron