Appends the given message at the end of the message list and delete the oldest one (top most).
        :param message: The formatted text to log.

def append_message(self,
                       message):
        """
        Appends the given message at the end of the message list and delete the oldest one (top most).
        :param message: The formatted text to log.
        """
        # Delete the first message of the list
        if len(self.messages) > 0:
            del self.messages[0]

        # Append the new message at the end
        self.messages.append(message)
        self.changes_made = True

        # Redraw
        self.redraw()