web/web_x2m_filter/demo/res_groups.xml

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
    <data>
        <record id="view_groups_form" model="ir.ui.view">
            <field name="model">res.groups</field>
            <field name="inherit_id" ref="base.view_groups_form" />
            <field name="arch" type="xml">
                <field name="users" position="attributes">
                    <attribute name="options">{'web_x2m_filter': [{'name': 'Only admins', 'domain': [('groups_id', '=', %(base.group_erp_manager)s)], 'default': True}]}</attribute>
                </field>
            </field>
        </record>
    </data>
</openerp>