Version 1.3.4
When exporting data into CSV the Content-Type header is set to "text/html". This causes some browsers to download the file as .htm instead of as .csv.
Change the following line in the administrator\components\com_ckforms\controllers\ckdata.php file:
header( "Content-type: application/vnd.ms-excel");
to:
$document->setMimeEncoding('application/vnd.ms-excel');