eiru_service_carworkshop/views/project_service.xml

<?xml version="1.0"?>
<openerp>
    <data>

        <!-- Form view -->

        <record model="ir.ui.view" id="project_service_inherit">
            <field name="name">project.service.form.inherit</field>
            <field name="model">project.service</field>
            <field name="inherit_id" ref="eiru_service.project_service_form"/>
            <field name="arch" type="xml">
                <field name="partner_id" position="after">
                    <field name="policy" string="¿Entra por medio de seguro?" attrs="{'readonly': [('state','=', 'close')]}"/>
                </field>
                <field name="policy" position="after">
                    <field name="agent_id" string="Agente de seguro" attrs="{'invisible': [('policy','=', False)],'readonly': [('state','=', 'close')]}"/>
                </field>
            </field>
        </record>

    </data>
</openerp>