app-odoo/app_documents_superbar/views/documents_folder_views.xml

<odoo>
    <record id="app_folder_view_search" model="ir.ui.view">
        <field name="name">documents.folder.search</field>
        <field name="model">documents.folder</field>
        <field name="inherit_id" ref="documents.folder_view_search"/>
        <field name="arch" type="xml">
            <xpath expr="//search">
                <searchpanel>
                    <field name="parent_folder_id" select="multi"/>
                </searchpanel>
            </xpath>
        </field>
    </record>
</odoo>