private function _checkfiles()
    {
        if (!file_exists($this->_plugin_base."js/".strtolower($this->_plugin_name).".js")) {
            $this->global_error->addError("file_exists(".$this->_plugin_base."js/".strtolower($this->_plugin_name).".js)", "JS-File for Plugin '".$this->_plugin_name."' is missing!");
        } else {
            if (!is_readable($this->_plugin_base."js/".strtolower($this->_plugin_name).".js")) {
                $this->global_error->addError("is_readable(".$this->_plugin_base."js/".strtolower($this->_plugin_name).".js)", "JS-File for Plugin '".$this->_plugin_name."' is not readable but present!");
            }
        }
        if (!file_exists($this->_plugin_base."lang/en.xml")) {
            $this->global_error->addError("file_exists(".$this->_plugin_base."lang/en.xml)", "At least an english translation must exist for the plugin!");
        } else {
            if (!is_readable($this->_plugin_base."lang/en.xml")) {
                $this->global_error->addError("is_readable(".$this->_plugin_base."js/".$this->_plugin_name.".js)", "The english translation can't be read but is present!");
            }
        }
    }