docker-roundcube-server/roundcube/roundcubemail-1.2.2/skins/classic/includes/taskbar.html

<div id="taskbar">
<roundcube:button command="mail" label="mail" class="button-mail" />
<roundcube:button command="addressbook" label="addressbook" class="button-addressbook" />
<roundcube:container name="taskbar" id="taskbar" />
<roundcube:button command="settings" label="settings" class="button-settings" />
<roundcube:button command="logout" label="logout" class="button-logout" />
</div>