clicked the 'Open CSS Dialog" in a CSS file and got this:

http://screencast.com/t/kzCfCkRp

with this error: "null
Warning
Sun Jun 09 16:08:36 EDT 2013
Xulrunner implementation hasn't been founded, so browser based preview will be not available
"

The error message is not correct/proper but more surprising is that it seems we got multiple ways of using browser preveiw.

Jquery mobile works fine, css does not.