Eudora circa '96 or so. I loved that it had personality. If you started typing without any window open it would beep for the first several keystrokes and then a

Eudora circa '96 or so. I loved that it had personality. If you started typing without any window open it would beep for the first several keystrokes and then a dialog would pop up after a bit that said something like "You can continue typing but no one is listening right now." In later versions it was changed to some terse message like "No window open to receive input" and it popped up once for every keystroke, instead of waiting til the 5 keystroke or so.