Use the clipboard to send a string.

def _send_string_clipboard(self, string: str, paste_command: model.SendMode):
        """
        Use the clipboard to send a string.
        """
        backup = self.clipboard.text  # Keep a backup of current content, to restore the original afterwards.
        if backup is None:
            logger.warning("Tried to backup the X clipboard content, but got None instead of a string.")
        self.clipboard.text = string
        try:
            self.mediator.send_string(paste_command.value)
        finally:
            self.ungrab_keyboard()
        # Because send_string is queued, also enqueue the clipboard restore, to keep the proper action ordering.
        self.__enqueue(self._restore_clipboard_text, backup)