title: How do I add buttons and fields on the header of the Kanban view with ODOO 12?
body: <p>I'm working on odoo 12, I tried to add a field or a button like on the header of the Kanban view (product_template view) in order to add searching filters like those:</p>
  
  <p><a href="https://i.stack.imgur.com/yCd9t.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yCd9t.png" alt="enter image description here"></a></p>
  
  <p>I tried this code:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;templates id="template" xml:space="preserve"&gt;
      &lt;t t-extend="KanbanView.buttons"&gt;
          &lt;t t-jquery="button.oe_kanban_add" t-operation="after"&gt;
              &lt;t t-if="widget.model == 'product.template'"&gt;
                  &lt;button&gt;
                      class="oe_button oe_highlight"
                      type="button"&gt;My Button&lt;/button&gt;
              &lt;/t&gt;
          &lt;/t&gt;
      &lt;/t&gt;
  &lt;/templates&gt;
  </code></pre>
  
  <p>And this code:</p>
  
  <pre><code>&lt;odoo&gt;
      &lt;record id="view_kanban_gimmo" model="ir.ui.view"&gt;
              &lt;field  name="name"&gt;Searching&lt;/field&gt;
              &lt;field  name="model"&gt;product.template&lt;/field&gt;
              &lt;field  name="inherit_id" ref="product.product_template_kanban_view"/&gt;
  
              &lt;field  name="arch" type="xml"&gt;
                  &lt;xpath expr="." position="inside"&gt;
                      &lt;header position="inside"&gt;
                          &lt;button
                      class="oe_button oe_highlight"
                      type="button"&gt;My Button&lt;/button&gt;
                      &lt;/header&gt;
                  &lt;/xpath&gt;
                  &lt;/field&gt;
          &lt;/record&gt;
  &lt;/odoo&gt;
  </code></pre>
  
  <p>But it's not working.</p>