partner-contact/partner_financial_risk/views/account_invoice_view.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2016 Carlos Dauden <carlos.dauden@tecnativa.com>
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl-3). -->
<openerp>
<data>
<record id="invoice_partner_risk_form" model="ir.ui.view">
    <field name="name">account.invoice.partner.risk.form</field>
    <field name="model">account.invoice</field>
    <field name="inherit_id" ref="account.invoice_form"/>
    <field name="arch" type="xml">
            <button name="invoice_open" position="attributes">
                <attribute name="type">object</attribute>
            </button>
    </field>
</record>
</data>
</openerp>