I want to put a menu icon for the hr_attendance addon.

I will explain the steps that i have done:

1. Create hr_attendance_extend an put it in addon_extra

2. Import the original addon. This is "__init__.py:

import hr_attendance

3. Create the css and put the icon. This is a piece of the file "static/src/css/slider.css":

...
.oe_systray .oe_attendance_signout {
    float:right;
    height: 32px;
    width: 32px;
    background: url(/hr_attendance_extend/static/src/img/emp-in32.png);
    cursor: pointer;
}
...

4. Link the file with the addon. This is the file ''views/hr_attendance.xml":

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
        <template id="assets_backend" name="hr_attendance assets" inherit_id="web.assets_backend">
            <xpath expr="." position="inside">
                 <link rel="stylesheet" href="/hr_attendance_extend/static/src/css/slider.css"/>
            </xpath>
        </template>
    </data>
</openerp>

5. Put the new files in the new addon. This is part of the file "__openerp__.py":

{
...
'depends': ['hr_attendance'],
    'data': [
        'hr_attendance.xml',
        'views/hr_attendance.xml',
    ],
    'demo': [],
    'test': [],
    'installable': True,
    'auto_install': False,
    #web 
    'qweb' : ["static/src/xml/attendance.xml"],
}

6. Put the container for the menu. This is the file ''static/src/xml/attendance.xml":

<template>
    <t t-name="AttendanceSlider">
	<li class="oe_attendance_status oe_attendance_nosigned" data-toggle="tooltip">
              <div class="oe_attendance_signout"></div>
        </li>
    </t>
</template>

In the original addon (hr_attendance) there is a function that it pushes the icon to the menu (I think). 

There is in the file static/src/js/attendance.js and that is the line in question:

SystrayMenu.Items.push(AttendanceSlider);

That's all.

I don't know if I am missing something.  The code of the icon appears in the html, but there is with 'style="display: none"'