Pointer to a HandlerDesc data structure, into which the macro will
copy the remaining parameters.
Pointer to the callback function that BREW will call when processing
events for this object. This routine will override the default event
handler for the object, allowing an application to handle various
events in a custom manner.
A pointer to private data allocated and managed by the caller that
has registered the handler. This data pointer is passed into the
custom event handler, as well as the free handler, providing each of
these callbacks with access to this private storage.
Pointer to the callback function that BREW will call when freeing the
memory associated with a handler upon release of the object implementing
the handler interface. This gives the object the opportunity to release
any private "deep storage" that may have been allocated by the object.