Hi,
I think the problem is linked with your template.
The popup display an iframe with a special page (productmarket cartlink).
This page does not have a view, it just return two text areas (you can see the function in the controller components/com_hikamarket/controllers/product.php - function cartlink).
So I think that your template is overriding the textarea display to make it like that ; the text area should be bigger (4 rows and 5 rows)
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.