public function add_after($name, $label = '', array $attributes = array(), array $rules = array(), $fieldname = null)
	{
		$field = $this->add($name, $label, $attributes, $rules);

		// Remove from tail and reinsert at correct location
		unset($this->fields[$field->name]);
		if ( ! \Arr::insert_after_key($this->fields, array($field->name => $field), $fieldname, true))
		{
			throw new \RuntimeException('Field "'.$fieldname.'" does not exist in this Fieldset. Field "'.$name.'" can not be added.');
		}

		return $field;
	}