If the gconf var use_scrollbar be changed, this method will
        be called and will show/hide scrollbars of all terminals open.

def scrollbar_toggled(self, settings, key, user_data):
        """If the gconf var use_scrollbar be changed, this method will
        be called and will show/hide scrollbars of all terminals open.
        """
        for term in self.guake.notebook_manager.iter_terminals():
            # There is an hbox in each tab of the main notebook and it
            # contains a Terminal and a Scrollbar. Since only have the
            # Terminal here, we're going to use this to get the
            # scrollbar and hide/show it.
            hbox = term.get_parent()
            if hbox is None:
                continue
            terminal, scrollbar = hbox.get_children()
            if settings.get_boolean(key):
                scrollbar.show()
            else:
                scrollbar.hide()