AdiIRC

Starting with the newest beta, AdiIRC can detect the state of the Insert key. I wrote a script for that because I hate negative surprises.

alias -l inskeywindow {
  ; Create the notifier window
  window -Cdpw0 +dL @InsertKeyNotifier 250 250 300 100

  ; Fill and show
  drawfill @InsertKeyNotifier 0 0 1 1 300 100
  drawtext @InsertKeyNotifier 1 "Segoe UI" 50 20 14 Insert is $iif($keylocked(Insert), on, off)
}

on *:KEYUP:*:*:{
  if ($keyval = 45) {
    inskeywindow
    .timer -m 1 500 window -c @InsertKeyNotifier
  }
}