Paste on Remotes and type /nc to configure your own nick completion

on *:input:#: {
  if ($left($1,1) != $chr(47)) {
    var %acro 1
    var %text $1-
    while (%acro <= $numtok(%text,32)) {
      if ($gettok(%text,%acro,32) ison $chan) { 
        var %nick = $nick($chan,$nick($chan,$ifmatch))
      var %text = $replace(%text,%nick,$+(,%nc1,%nick,%nc2 $+ ,)) }
      inc %acro
    }
    say %text
    halt
  }
}

dialog completion {
  title "Instinct Completion"
  size -1 -1 83 30
  option dbu
  edit %nc1, 1, 2 3 27 10, autohs
  edit "Nick", 2, 28 3 27 10, read center
  edit %nc2, 3, 54 3 27 10, return
  button "Apply", 4, 2 15 39 12, flat ok
  button "Cancel", 5, 41 15 39 12, flat cancel
  box "", 6, 1 -1 81 15
  box "", 7, 0 -2 83 32
  box "", 8, 1 11 81 18
}

alias nc { dialog -m completion completion }

on *:dialog:completion:sclick:4: {
  set %nc1 $did(1).text 
  set %nc2 $did(3).text
}