pre-on-event

Called when this window or a child window receives a mouse event. The top-most parent's pre-on-event method is called first; if the return value is #f, the pre-on-event method is called for the next child in the path to the receiver. Finally, if the receiver's pre-on-event method returns #f, the event is passed on to the receiver's normal mouse-handling mechanism.

• (send a-wx:window pre-on-event receiver event) -> boolean
      receiver : wx:window% object
      event : wx:key-event% object

  The event argument is the event that was generated for the receiver window.