mail-addons/mail_todo_custom/mail_todo_custom.xml

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

        <template id="assets_backend_inherited_mail_todo_custom" name="Mail todo custom" inherit_id="web.assets_backend">
            <xpath expr="." position="inside">
                <script type="text/javascript" src="/mail_todo_custom/static/src/js/mail_todo_custom.js"></script>
            </xpath>
        </template>

        <record id="mail.action_mail_star_feeds" model="ir.actions.client">
            <field name="context">
                {
                    'default_model': 'res.users',
                    'default_res_id': uid,
                    'thread_model': 'res.partner',
                    'search_default_message_unread': False,
                    'view_todo': True
                }
            </field>
        </record>


     </data>
</openerp>