pos/pos_customer_display/customer_display_view.xml

<?xml version="1.0"?>
<openerp>
    <data>
        <record id="view_pos_config_form2" model="ir.ui.view">
            <field name="name">pos.config.form.view.inherit</field>
            <field name="model">pos.config</field>
            <field name="inherit_id" ref="point_of_sale.view_pos_config_form"/>
            <field name="arch" type="xml">
                <field name="iface_cashdrawer" position="after">
                    <field name="iface_customer_display"/>
                    <field name="customer_display_line_length"/>
                </field>
            </field>
        </record>
    </data>
</openerp>