invoice.xml

<?xml version='1.0'?>
<!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
this repository contains the full copyright notices and license terms. -->
<tryton>
    <data depends="account_invoice,account_payment">
        <record model="ir.ui.view" id="move_line_view_list_to_pay">
            <field name="model">account.move.line</field>
            <field name="inherit" ref="account_invoice.move_line_view_list_to_pay"/>
            <field name="name">move_line_list_to_pay</field>
        </record>
    </data>
    <data depends="account_invoice">
        <record model="ir.ui.view" id="invoice_view_form">
            <field name="model">account.invoice</field>
            <field name="inherit" ref="account_invoice.invoice_view_form"/>
            <field name="name">invoice_form</field>
        </record>

        <record model="ir.model.button" id="invoice_unpay_button">
            <field name="model">account.invoice</field>
            <field name="name">unpay</field>
            <field name="string">Void Payment</field>
            <field name="confirm">This action will remove all the payments done directly to the invoice from the PAY button. Are you sure you want to continue?</field>
        </record>
        <record model="ir.model.button-res.group"
                id="invoice_unpay_button_group_account">
            <field name="button" ref="invoice_unpay_button"/>
            <field name="group" ref="account.group_account"/>
        </record>
    </data>
</tryton>