server-tools/mail_client_view/view/mail_user_view.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
        <record
            id="view_mail_action_needed_search"
            model="ir.ui.view">
            <field name="name">view_mail_action_needed_search</field>
            <field name="model">mail.message</field>
            <field
                name="inherit_id"
                ref="mail.view_email_message_search" />
            <field
                name="arch"
                type="xml">
                <data>
                    <field
                        name="email_from"
                        position="before">
                        <separator orientation="vertical"/>
                        <filter
                            icon="terp-check"
                            name="action"
                            string="Action needed"
                            domain="[('action_needed','=',True)]" />
                    </field>
                </data>
            </field>
        </record>
        <record
            id="view_mail_action_needed_tree"
            model="ir.ui.view">
            <field name="name">view_mail_action_needed_tree</field>
            <field name="model">mail.message</field>
            <field
                name="inherit_id"
                ref="mail.view_email_message_tree" />
            <field
                name="arch"
                type="xml">
                <data>
                    <field
                        name="state"
                        position="after">
                        <field
                            name="action_needed"
                            invisible="True" />
                        <button
                            name="set_action_needed_off"
                            attrs="{'invisible': [('action_needed','=',False)]}"
                            string="confirm action done"
                            icon="gtk-no"
                            type="object" />
                        <button
                            name="set_action_needed_on"
                            attrs="{'invisible': [('action_needed','=',True)]}"
                            string="set action needed"
                            icon="gtk-yes"
                            type="object" />
                    </field>
                </data>
            </field>
        </record>
        <record
            id="view_mail_action_needed_form"
            model="ir.ui.view">
            <field name="name">view_mail_action_needed_form</field>
            <field name="model">mail.message</field>
            <field
                name="inherit_id"
                ref="mail.view_email_message_form" />
            <field
                name="arch"
                type="xml">
                <data>
                    <button
                        name="%(mail.action_email_compose_message_wizard)d"
                        position="after">
                        <field
                            name="action_needed"
                            invisible="True" />
                        <button
                            name="set_action_needed_off"
                            attrs="{'invisible': [('action_needed','=',False)]}"
                            string="confirm action done"
                            icon="gtk-no"
                            type="object" />
                        <button
                            name="set_action_needed_on"
                            attrs="{'invisible': [('action_needed','=',True)]}"
                            string="set action needed"
                            icon="gtk-yes"
                            type="object" />
                    </button>
                </data>
            </field>
        </record>
    </data>
</openerp>