title: prestashop show helper form checkbox checked
body: <p>In Prestashop module I want to show a checkbox checked. For that I just took the helper class methods like this</p>
  
  <pre><code>$display_settings = array(
              'form' =&gt; array(
                  'legend' =&gt; array(
                      'title' =&gt; $this-&gt;l( 'Display Settings' ),
                      'icon' =&gt; 'icon-cogs'
                  ),
                  'input' =&gt; array(
                  array(
                      'type' =&gt; 'checkbox',
                      'name' =&gt; 'display',
                      'values' =&gt; array(
                          'query' =&gt; array(
                              array(
                                  'id' =&gt; 'show_header',
                                  'name' =&gt; $this-&gt;l('show header'),
                                  'val' =&gt; '1',
                                  'checked' =&gt; 'checked'
                              ),
                          ),
                          'id' =&gt; 'id',
                          'name' =&gt; 'name'
                      )
                  ),
                  ),
                  'submit' =&gt; array(
                      'title' =&gt; $this-&gt;l( 'Save Display Settings' ),
                      'class' =&gt; 'button pull-right',
                      'name' =&gt; 'save-main-display-settings',
                  )
              ),
          );
  </code></pre>
  
  <p>but this one is showing only checkbow (not checked). I tried to chnage val into 0,1. But it did not worked for me. So can someone tell me how to make a checkbox checked in helper class. Any help or suggestions will be really  appreceable. Thanks</p>