How do I auto_refresh an XML tree view? I have a cron job working in the background that will change the state once a task is complete. I want the tree to update every 20 seconds so that the user will see the state change without refreshing the view.

How can I do this? Here is my code.

<record model="ir.ui.view" id="view_faxing_fax_tree">
    <field name="name">my.mod.tree</field>
    <field name="model">my.mod</field>
    <field name="type">tree</field>
    <field name="auto_refresh">20</field>
    <field name="arch" type="xml">
        <tree string="Faxes" colors="red:state=='send_except'; orange:state=='pending';">
            <field name="name"/>
            <field name="partner_id"/>
            <field name="create_date"/>
            <field name="state"/>
        </tree>
    </field>
</record>