l10n_it_account_stamp/views/product_view.xml
<?xml version="1.0" encoding="utf-8"?>
<openerp>
<data>
<record id="product_template_form_view_account_stamp" model="ir.ui.view">
<field name="name">product.template.form.inherit</field>
<field name="model">product.template</field>
<field name="inherit_id" ref="account.product_template_form_view"/>
<field name="arch" type="xml">
<page string='Accounting' position="inside">
<group string="Tax stamp">
<field name="is_stamp"/>
<p attrs="{'invisible': [('is_stamp', '=', False)]}" colspan="2">
For each invoice, the base amount for each selected tax will be added up and used to determine the application of the account stamp.
</p>
<field name="stamp_apply_min_total_base" attrs="{'invisible': [('is_stamp', '=', False)], 'required': [('is_stamp', '=', True)]}"/>
<field name="stamp_apply_tax_ids" attrs="{'invisible': [('is_stamp', '=', False)]}" widget="many2many_tags">
<tree>
<field name="description"/>
<field name="name"/>
</tree>
</field>
</group>
</page>
<xpath expr="//field[@name='property_account_income']" position="attributes">
<attribute name="attrs">{'required': [('is_stamp', '=', True)]}</attribute>
</xpath>
<xpath expr="//field[@name='property_account_expense']" position="attributes">
<attribute name="attrs">{'required': [('is_stamp', '=', True)]}</attribute>
</xpath>
</field>
</record>
</data>
</openerp>