account-financial-reporting/account_debtor_card/views/res_partner.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
        <report
                id="action_report_debtor_card"
                model="res.partner"
                string="Debtor Card"
                report_type="qweb-pdf"
                file="account_debtor_card.report_debtor_card"
                name="account_debtor_card.report_debtor_card"
        />
        <record id="view_partner_form_inherit" model="ir.ui.view">
            <field name="name">view.partner.form.inherit</field>
            <field name="model">res.partner</field>
            <field name="inherit_id" ref="base.view_partner_form"/>
            <field name="arch" type="xml">
                <xpath expr="//form/sheet" position="before">
                <header>
                    <button type="object" name="print_debtor_card"
                        string="Print Debtor Card"
                        attrs="{'invisible':[('sale_order_ids','=',[])]}"/>
                </header>
            </xpath>
                <notebook position="inside">
                    <page name="sale_orders" string="Sale Orders">
                        <field name="sale_order_ids"/>
                    </page>
                </notebook>
            </field>
        </record>
    </data>
</openerp>