trytond-stock_location_history_state/view/location_tree.xml

<?xml version="1.0"?>
<!-- The COPYRIGHT file at the top level of
this repository contains the full copyright notices and license terms. -->
<data>
    <xpath expr="/tree" position="inside">
        <field name="state" icon="state_icon"/>
        <button name="on"/>
        <button name="off"/>
    </xpath>
</data>