public function get_right_range_row($rows=array()) {
        global $OUTPUT;

        if ($this->get_pref('showranges')) {
            $rangesdisplaytype   = $this->get_pref('rangesdisplaytype');
            $rangesdecimalpoints = $this->get_pref('rangesdecimalpoints');
            $rangerow = new html_table_row();
            $rangerow->attributes['class'] = 'heading range';

            foreach ($this->gtree->items as $itemid => $unused) {
                $item =& $this->gtree->items[$itemid];
                $itemcell = new html_table_cell();
                $itemcell->attributes['class'] .= ' range i'. $itemid;

                $hidden = '';
                if ($item->is_hidden()) {
                    $hidden = ' dimmed_text ';
                }

                $formattedrange = $item->get_formatted_range($rangesdisplaytype, $rangesdecimalpoints);

                $itemcell->text = $OUTPUT->container($formattedrange, 'rangevalues'.$hidden);
                $rangerow->cells[] = $itemcell;
            }
            $rows[] = $rangerow;
        }
        return $rows;
    }