public function addSelectable($field)
    {
        $this->js_widget = null;
        $this->js(true)
            ->_load('ui.atk4_checkboxes')
            ->atk4_checkboxes(array('dst_field' => $field));
        $this->addColumn('checkbox', 'selected');

        $this->addOrder()
            ->useArray($this->columns)
            ->move('selected', 'first')
            ->now();
    }