Man pages matching name wslay_event_queue_msg_ex in section 3:

wslay_event_queue_msg_ex.3.en	debian 10 / libwslay-doc
wslay_event_queue_msg_ex.3.en	debian 11 / libwslay-doc
wslay_event_queue_msg_ex.3.en	debian 12 / libwslay-doc