Domain access domain menu show default values
I found a workaround. I just rebuild the options array with the domains the user has admin access to.
Here is my code:

// Alter the edit menu item form


if($form_id == 'menu_edit_item'){
    $form['domain_menu_access']['manage']['#collapsed'] = false;
    $domains = array();
    if($user-&gt;uid &gt; 1){

  // We don't need to hide any menu items on other domains so we don't show this option.
  $form['domain_menu_access']['manage']['domain_menu_access_hide']['#access'] = false;

  // Loop the user object for all the domains current user is connected to
  foreach($user-&gt;domain_user as $domain){
    // Get the domain data
    $domains[] = domain_lookup($domain);

    // First unset all the options of the form element so we can rebuild it with our own values
    unset($form['domain_menu_access']['manage']['domain_menu_access_show']['#options']);
    //Rebuild the #options array
    $form['domain_menu_access']['manage']['domain_menu_access_show']['#options']['d'.$domain] = $domains[0]['sitename'];

    // Set the default value(s)
    $form['domain_menu_access']['manage']['domain_menu_access_show']['#default_value'] = array('d'.$domain);
  }
}


}