I am using: You are using a development version (3.5-alpha-21460)
When I click 'preview' on a child theme, I get the following error.
Fatal error: Call to a member function process_default_headers() on a non-object in /home/lipslimreviews/public_html/wp-includes/class-wp-customize-control.php on line 755
this happens on every child theme I create. Does not happen on standard WordPress vs.
Not sure if there is a fix for this as of yet, just reporting it as I like to run trunk when I can