'Save configuration: tree widget state'

def save_config(self):

    for (option, value) in list(self.explorer.get_options().items()):
        self.set_option(option, value)
    self.set_option('expanded_state', self.explorer.treewidget.get_expanded_state())
    self.set_option('scrollbar_position', self.explorer.treewidget.get_scrollbar_position())
