I've noticed that setEventMessage is now a deprecated function and setEventMessages should be used instead.
Its signature is
function setEventMessages($mesg, $mesgs, $style='mesgs')
where $mesg is for a string and $mesgs is filled when we want to attach an array of messages.
My question is... why doing this and not doing a setEventMessage where the first param can be either an array or a string? I must say I don't really like functions that act differently depending on 1st or 2nd param filled.