Set user data for the dictionary returned with the last event
#include <mm/events.h>
int mmr_event_data_set(mmr_context_t *ctxt, void *usrdata)
Set user data to associate with the dictionary returned with the last event. The dictionary contains all of the mm-renderer properties reported by this event and gets stored in the data field of the mmr_event_t structures returned for subsequent events.
Zero on success, or -1 if there is no longer a pending event or the last event was a deletion