<?xml version="1.0"?>
<data>
               <xpath expr="//button[@name='action_view_invoice']" position="before">
                   <button type="action" name="624" class="oe_stat_button" icon="fa-money" attrs="{'invisible': [('expense_count', '=', 0)]}">
                       <field name="expense_count" widget="statinfo" string="Expenses"/>
                   </button>
                </xpath>
            </data>
        