Toggle show current directory only mode

def toggle_show_cd_only(self, checked):
        """Toggle show current directory only mode"""
        self.parent_widget.sig_option_changed.emit('show_cd_only', checked)
        self.show_cd_only = checked
        if checked:
            if self.__last_folder is not None:
                self.set_current_folder(self.__last_folder)
        elif self.__original_root_index is not None:
            self.setRootIndex(self.__original_root_index)