home_pro_ticket/views/button_view.xml

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
	<data>
		<record id="view_account_invoice_form_ticket" model="ir.ui.view">
            <field name="name">view.account.invoice.form.ticket</field>
            <field name="model">account.invoice</field>
            <field name="inherit_id" ref="account.invoice_form"/>
            <field name="arch" type="xml">
				<xpath expr="//button[@name='invoice_print']" position="replace">
					<div class="eiru-print-ticket" style="width:auto;float: left;"> </div>
				</xpath>
            </field>
        </record>
	</data>
</openerp>