Usage: prompt_popup -message MESSAGE -button HELLO
  -message MESSAGE: Pops a window prompting the user with MESSAGE.
                    Program does not return until user responds.
                    note: if MESSAGE is '-', it is read from stdin
  -pause MESSAGE:   Same as -message to match the old prompt_user
  -button LABEL:    What do you want the buttons to say?
                    You can give up to three -button for three buttons.
                    Returns integer 1, 2, or 3.
                    If there is no -button, there will be one button 'Ok'
  -b LABEL:         Same as -button.
  -timeout TT:      Timeout in seconds of prompt message. Default answer
                    is returned if TT seconds elapse without user
  -to TT:           Same as -timeout TT

example: prompt_popup -message 'Best disco ever?' -b Earth -b Wind -b Fire