def unhandled(self, key):
        """Handle other keyboard actions not handled by the ListBox widget.

        """
        self.key = key
        self.size = self.tui.get_cols_rows()
        if self.search is True:
            if self.enter is False and self.no_matches is False:
                if len(key) == 1 and key.isprintable():
                    self.search_string += key
                self._search()
            elif self.enter is True and not self.search_string:
                self.search = False
                self.enter = False
            return
        if not self.urls and key not in "Qq":
            return  # No other actions are useful with no URLs
        if self.help_menu is False:
            try:
                self.keys[key]()
            except KeyError:
                pass
Handle other keyboard actions not handled by the ListBox widget.