purchase_view.xml

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
    <data>
        
        <record id="purchase.purchase_rfq" model="ir.actions.act_window">
            <field name="context">{'purchase_rfq': True}</field>
        </record>

        <record id="purchase_order_form" model="ir.ui.view">
            <field name="model">purchase.order</field>
            <field name="inherit_id" ref="purchase.purchase_order_form"/>
            <field name="arch" type="xml">
                <field name="currency_id" position="after">
                    <field name="picking_state"
                           attrs="{'invisible':[('picking_state','=', 'draft')]}"/>
                </field>
            </field>
        </record>

        <record id="purchase_order_tree" model="ir.ui.view">
            <field name="model">purchase.order</field>
            <field name="inherit_id" ref="purchase.purchase_order_tree"/>
            <field name="arch" type="xml">
                <field name="state" position="after">
                    <field name="picking_state"
                           invisible="context.get('purchase_rfq')"/>
                </field>
            </field>
        </record>

    </data>
</openerp>