category_expense/views/category_view.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
<data>

	<record model="ir.ui.view" id="product_category_form">
		<field name="name">product.category.form</field>
		<field name="model">product.category</field>
		<field name="inherit_id" ref="product.product_category_form_view"/>
		<field name="arch" type="xml">
			<field name="parent_id" position="before">
				<field name="expense" string="¿Es una categoria de gasto?"/>
			</field>
		</field>
	</record>
</data>
</openerp>