[Meta]

You mean Alt + F4?
better would be, as suggested too much, detection of ANY key

pawn Код:

if(PressedKey(playerid) == "E")
//OR
if(PressedKey(playerid, "E") == true)

//OR!

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys, keyname[])
{
    if(strfind(keyname, "O") != -1) { SendClientMessageEx(playerid, 0xFFFFFFFF, "You Pressed 'O'"); }
}

So that keyname would include the keynames
example: i press U, R and F:

pawn Код:

keyname == "URF"

F1, Alt and stuff have to be saved with [] then (as [ALT] or [F1])

pawn Код:

keyname == "URF[Alt]P[F8]"

etc ...

but then serverowners could script keyloggers :O