pub fn on_event(event_type: &str, callback_id: u32) -> u32Expand description
Register a listener for events of event_type. When an event fires, the
host invokes the guest-exported on_event(callback_id) and exposes the
event payload via event_type / event_data.
Returns a non-zero listener ID for off_event, or 0 on failure
(empty event type, missing memory).