sale_discount_total/views/sale_discount_approval_view.xml

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

        <record id="view_double_sale_configuration" model="ir.ui.view">
            <field name="name">Sale Application</field>
            <field name="model">sale.config.settings</field>
            <field name="inherit_id" ref="sale.view_sales_config"/>
            <field name="arch" type="xml">
                    <xpath expr="//div[@name='Sale Features']" position="inside">

                        <div>
                            <div name="module_sale_discount_approval">
                               <field name="module_sale_discount_approval" class="oe_inline"/>
                               <label for="module_sale_discount_approval"/>
                                <span class="oe_separate-from-text">
                                   <label for="limit_discount"/>
                                   <field name="limit_discount" attrs="{'required': [('module_sale_discount_approval','=',True)]}" class="oe_inline"/>
                               </span>
                            </div>

                        </div>
                </xpath>
            </field>
        </record>

    </data>
</openerp>