Dialog::unread

static function unread($dialogId, $messageId = null, $userId = null)
{
	$userId = BitrixImCommon::getUserId($userId);
	if (!$userId)
	{
		return false;
	}

	if (BitrixImCommon::isChatId($dialogId))
	{
		$chatId = self::getChatId($dialogId);

		$chat = new CIMChat($userId);
		$chat->SetUnReadMessage($chatId, $messageId);
	}
	else
	{
		$CIMMessage = new CIMMessage($userId);
		$CIMMessage->SetUnReadMessage($dialogId, $messageId);
	}

	return false;
}