title: How can I add images or icons in a tree view inside a custom module in odoo 9?
body: <p>I want to put an image inside a button in a tree view of a custom module in odoo 9.</p>
  
  <p>I have 2 buttons in my_module.xml:</p>
  
  <pre><code>&lt;?xml version="1.0"?&gt;
  &lt;openerp&gt;
      &lt;data&gt;
          &lt;record id="view_my_module_tree" model="ir.ui.view"&gt;
              &lt;field name="name"&gt;my.module.tree&lt;/field&gt;
              &lt;field name="model"&gt;my.module&lt;/field&gt;
              &lt;field name="type"&gt;tree&lt;/field&gt;
              &lt;field name="arch" type="xml"&gt;
                  &lt;tree string="my_module_tree" create="false" delete="false"&gt;
                      &lt;button name="button_form" icon="cat" type="object"/&gt;
                      &lt;button name="button_form" icon="dog" type="object"/&gt;                   
                  &lt;/tree&gt;
              &lt;/field&gt;
          &lt;/record&gt;  
      &lt;/data&gt;
  &lt;/openerp&gt;
  </code></pre>
  
  <p>That works if the icons 'cat.png' and dog.png' are inside 'addons/web/static/src/img/icons/'. But I want to put this icons in my custom module.</p>
  
  <p>I have created the 'my_module/static/src/img/icons/' hierarchy and put both images inside, but none of them appear in the buttons.</p>
  
  <p>What I am doing wrong? 
  Do I need to put something in openerp.py file?</p>
  
  <p><strong>Edit:</strong> I have tried this </p>
  
  <pre><code>&lt;button name="button_form" type="object" icon="/my_module/static/src/img/icons/cat.png"/&gt; 
  </code></pre>
  
  <p>But it doesn't work. If I see in the browser DevTools, I can check in the html code that: </p>
  
  <pre><code>&lt;img src="http://localhost:8069/web/static/src/img/icons//my_module/static/src/img/icons/cat.png.png"&gt;
  </code></pre>
  
  <p>That has sense with the source code of the WidgetButton (it appends to '/web/static/src/img/icons/' your image path, and then adds '.png' at the end But of course, that doesn't solve the problem.</p>