Bool wxAddPrimaryEventHandler(wxEventHandler handlerFunc)
Add a primary event handler---the normal event handler for this event. For built-in events, these would include moving and resizing windows. User-defined primary events might include the code to select an image in a diagram (which could of course be achieved by a series of external events for mouse-clicking, but would be more difficult to specify and less robust).
Returns TRUE if it succeeds.
An event handler takes a pointer to a wxEvent and a boolean flag which is TRUE if the event was externally generated, and returns a boolean which is TRUE if that event was handled.