'Toggle show current directory only mode'

@Slot(bool)
def toggle_show_cd_only(self, checked):

    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)
