social/mail_edit/views/res_request_link.xml

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

<openerp>
    <data>

        <record id="res_request_link_view_form" model="ir.ui.view">
            <field name="name">Add option to edit mails</field>
            <field name="model">res.request.link</field>
            <field name="inherit_id" ref="base.res_request_link-view"/>
            <field name="arch" type="xml">
                <xpath expr="//field[@name='priority']" position="after">
                    <field name="mail_edit"/>
                </xpath>
            </field>
        </record>

        <record id="res_request_link_view_tree" model="ir.ui.view">
            <field name="name">Add option to edit mails</field>
            <field name="model">res.request.link</field>
            <field name="inherit_id" ref="base.res_request_link_tree-view"/>
            <field name="arch" type="xml">
                <xpath expr="//field[@name='object']" position="after">
                    <field name="mail_edit"/>
                </xpath>
            </field>
        </record>

    </data>
</openerp>