<openerp>
    <data>
        <record model="ir.ui.view" id="invoice_form_add_condition">
            <field name="name">account.invoice.form.condition</field>
            <field name="model">account.invoice</field>
            <field name="inherit_id" ref="account.invoice_form"/>
            <field name="arch" type="xml">

                <xpath expr="//field[@name='invoice_line']" position="before">
                    <label for="note1"/>
                    <field name="note1" colspan="4"/>
                    <group>
                        <div>Use template
                            <field name="condition_template1_id"
                                nolabel="1"
                                class='oe_inline'
                                domain="[('position','=','before_lines')]"/>
                        </div>
                    </group>
                </xpath>

                <xpath expr="//field[@name='comment']" position="replace">
                    <field name="comment" colspan="4"/>
                    <label for="note2"/>
                    <field name="note2" colspan="4"/>
                    <group>
                        <div>Use template
                            <field name="condition_template2_id"
                                nolabel="1"
                                class='oe_inline'
                                domain="[('position','=','after_lines')]"/>
                        </div>
                    </group>
                </xpath>

            </field>
        </record>
    </data>
</openerp>

<openerp>
  <data>
    <record model="ir.ui.view" id="invoice_form_add_condition">
      <field name="name">account.invoice.form.condition</field>
      <field name="model">account.invoice</field>
      <field name="inherit_id" ref="account.invoice_form"/>
      <field name="arch" type="xml">

        <xpath expr="/form/sheet/notebook/page[3]" position="after">
          <page string="Comments" name="comments">
            <label string="The comments will be displayed on the printed document. You can load a predefined template, write your own text or load a template and then modify it only for this document." colspan="2"/>
            <group string="Top Comments">
              <field name="condition_template1_id"
                string="Load a template"
                domain="[('position','=','before_lines')]"
                context="{'default_position': 'before_lines'}"/>
              <field name="note1" nolabel="1" colspan="2"/>
            </group>
            <group string="Bottom Comments">
              <field name="condition_template2_id"
                string="Load a template"
                context="{'default_position': 'after_lines'}"
                domain="[('position','=','after_lines')]"/>
              <field name="note2" nolabel="1" colspan="2"/>
            </group>
          </page>
        </xpath>

      </field>
    </record>
  </data>
</openerp>

Move the comments fields in a page
Move the comments fields in a page

They take too much place in the first page of the notebook.  Improved the
layout of these fields (use the same layout than sale_condition_template)
