protected function renderNew($offset=null) {
		$default_render = $this->default_render;

		if($offset === null)
			$offset = $this->size();

		if(!isset($this[$offset]))
			$field = $this->newField($offset);
		else
			$field = $this[$offset];
		if(!$field)
			return;

		if($default_render === null)
			$r = $this->renderField($field);
		else
			$r = $default_render($field);

		unset($this[$offset]);

		return $r;
	}