/**
  * create new skin for other
  * @param string $name: skin name
  * @param string $group: skin group
  * @param string $skin_name: provide skin name if not will get same from parent
  */
 function create($name, $group = null, $skin_name = '')
 {
     if (!isset($this->skins_manager[$name])) {
         if (!$skin_name) {
             $skin_name = $this->skin_name;
         }
         //inherit skin name from parent
         $skin = new self($this->widget_ref, $this->_apply_plugin, $this->skin_folder, $skin_name, $this->_default_skin_path);
         $skin->plugin_url = $this->plugin_url;
         //maintain some variable
         $skin->skinID = $name;
         //skin id
         $skin->is_main = false;
         //$this->is_main = false;
         //if($group) //allow empty group to clear group
         $skin->set_group($group, $this->group_name);
         //set skin group
         $skin->init();
         //initial
         $this->skins_manager[$name] = $skin;
         //add to manager
     }
     return $this->skins_manager[$name];
 }