muk_web/muk_web_theme_mail/static/src/xml/systray.xml

<?xml version="1.0" encoding="UTF-8"?>

<!--

    Copyright (c) 2017-2019 MuK IT GmbH.

    This file is part of MuK Backend Theme Mail 
    (see https://mukit.at).

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program. If not, see <http://www.gnu.org/licenses/>.

  -->

<templates id="template" xml:space="preserve">

	<t t-extend="mail.systray.MessagingMenu">
         <t t-jquery="a.dropdown-toggle" t-operation="replace">
            <a class="dropdown-toggle o-no-caret" data-toggle="dropdown" data-display="static" aria-expanded="false" title="Conversations" href="#" role="button" accesskey="m">
                <i class="fa fa-comments" role="img" aria-label="Messages"/> <span class="o_notification_counter badge badge-pill"/>
            </a>
        </t>
    </t>
    
   	<t t-extend="mail.systray.ActivityMenu">
         <t t-jquery="a.dropdown-toggle" t-operation="replace">
            <a class="dropdown-toggle o-no-caret" data-toggle="dropdown" data-display="static" aria-expanded="false" title="Activities" href="#" role="button" accesskey="t">
                <i class="fa fa-clock-o" role="img" aria-label="Activities"/> <span class="o_notification_counter badge badge-pill"/>
            </a>
        </t>
    </t> 

</templates>