public function renderFilterForm()
    {
        if (!$this->_filter) {
            // Disabled
            return false;
        }

        foreach ($this->_columns as $columnData) {
            $column = new Column($columnData);
            if ($column->searchable()) {
                // At least one column is searchable - form should be generated
                return true;
            }
        }

        return false;
    }