public boolean key_do_jump_lanuch_or_argument () {
    if (control_down) {         // `jump-to-register DIGIT'
      jump_to_register (keycode);
      return true;

    } else if (meta_down) {	// `lanuch-command'
      String command = pref.launch (keysym - '0');
      
      if (command == null) {
        alert_user ("Command not defined: " + (keysym - '0'));
        return true;
      }

      try {
        Runtime.getRuntime ().exec (command);
      } catch (java.io.IOException e) {
        alert_user ("Failed to launch " + command + ": " + e);
      }

      return true;
       
    } else {			// argument
      argument_present = true;

      if (keysym == '-') {
        argument_negative = true;
        return false;
      }
      
      int i = ((char) keysym) - '0';
      argument = argument * 10 + i;
      return false;
    }
  }