mail-addons/mail_to/templates.xml

<?xml version="1.0"?>
<!--Copyright 2016 x620 <https://github.com/x620>
    Copyright 2017 Ivan Yelizariev <https://it-projects.info/team/yelizariev>
    Copyright 2019 Artem Rafailov <https://it-projects.info/team/Ommo73/>
    License LGPL-3.0 (https://www.gnu.org/licenses/lgpl.html).-->
<openerp>
    <data>
        <template id="mail_to_assets_backend"
                  name="mail_to_assets_backend"
                  inherit_id="web.assets_backend">
            <xpath expr="." position="inside">
                <link rel="stylesheet" href="/mail_to/static/src/css/mail_to.css"/>
                <script src="/mail_to/static/src/js/mail_to.js" type="text/javascript"></script>
                <script src="/mail_to/static/src/js/test_mail_to.js" type="text/javascript"></script>
            </xpath>
        </template>
    </data>
</openerp>