I am evaluating this module. When investigating if there was a body class for themeing the popout window, I noticed the following output when viewing source:

I found the code in page-chat-popout.tpl.php:

if (function_exists('phptemplate_body_class')) print ' ' . phptemplate_body_class($left, $right); ">

I am using Garland.

Thanks for putting the themeing in a tpl file. As a result, this bug won't hold me up. I will copy the tpl file to my theme directory and make needed changes there.