Render a full entire html page from custom module I've searched/asked around without success.

I'm creating a custom Drupal 7 module, and I would like to render the code in an empty full template (not a page/node.tpl.php); by full template I mean a template containing the &lt;html&gt; tag.

Since now, I've used the following code but the template is rendered in page.tpl.php (render($page['content'])).  

function mymodule_theme() {
  return array(
    'adm_xyz' =&gt; array (
      'render element' =&gt; 'render',
      'template' =&gt; 'adm_xyz', //  template *.tpl.php
    ),
  );
}
Your callback in hook_menu() will by default call drupal_deliver_html_page() which in turn calls drupal_render_page() where the page.tpl.php comes from.

It is possible to implement your own "delivery callback" method, which will be called by drupal_deliver_page() this is how the ajax is delivered in D7