calendar in web client does not display all fields

in the calendar view of GTK, it is possible to display several information related to one record. For example, in hr_holidays we display the leaves with the user and the type using the following view definition:

        <record id="view_holiday_new_calendar" model="ir.ui.view">
            <field name="name">Leave Request</field>
            <field name="model">hr.holidays</field>
            <field name="type">calendar</field>
            <field name="arch" type="xml">
                <calendar string="Leave Request" color="user_id" date_start="date_from" date_stop="date_to">
                    <field name="user_id"/>
                    <field name="holiday_status_id"/>
                </calendar>
            </field>
        </record>

And the result in GTK is: https://docs.google.com/a/openerp.com/file/d/0B5l7xpR0ZvoCaXRUNzVwTGlRUzZlYmNOWVdHS0IwQQ/edit#

But in web (latest trunk), only the first field is displayed (here the user). and it's a bug.

thanks,
Quentin