Man pages matching name al_show_native_message_box in section 3alleg5:

al_show_native_message_box.3alleg5.en	debian 10 / allegro5-doc
al_show_native_message_box.3alleg5.en	debian 11 / allegro5-doc
al_show_native_message_box.3alleg5.en	debian 12 / allegro5-doc