I added a button in crm.lead form in order to create a new object I defined based on the values of the Lead. I successfully can open a form in a popup (target=new) with predefined values (using the context and default_ values). However, there is no Create button showing up, I can therefore not save my new record. Do you know how to add this Create button ? Here is my XML:

<!-- Create Event action -->
        <record id="action_crm_make_event" model="ir.actions.act_window">
          <field name="name">Create Event</field>
          <field name="type">ir.actions.act_window</field>
          <field name="res_model">crm.event.custom</field>
          <field name="view_type">form</field>
          <field name="view_mode">form</field>
          <field name="target">new</field>
       </record>

<!-- Button for creating event based on existing Lead -->

<button string="Create Event" name="%(action_crm_make_event)d" type="action"

                 context="{'default_name': name, ...}"/>