/**
  * Gets a list of themes associated with the site type of the current theme
  * 
  * @param boolean $omit_current defaults to true, set to false if you want to include the current theme as well
  * @return array
  */
 function get_site_type_themes($omit_current = true)
 {
     $current_theme = $this->get_current_theme();
     //get site types
     $e = new entity($this->admin_page->site_id);
     $e->set_env('site', $this->admin_page->site_id);
     $site_types = $e->get_left_relationship('site_to_site_type');
     if (empty($site_types)) {
         return array();
     }
     $site_type_ids = array();
     foreach ($site_types as $st) {
         $site_type_ids[] = $st->id();
     }
     //get themeses
     $es = new entity_selector();
     $es->add_type(id_of('theme_type'));
     $es->add_right_relationship($site_type_ids, relationship_id_of('site_type_to_theme'));
     if ($current_theme and $omit_current) {
         $es->add_relation('entity.id !=' . $current_theme->id());
     }
     $es->set_order('entity.name ASC');
     return $es->run_one();
 }