[RCU] 1.5.0 New Feature, Message Header Question

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In 1.5.0 when viewing an email message, the top of the message by 
default displays a "summary" of headers showing only "From:" and 
"Date:". If you click the "Details" button it will expand and show all 
of the headers.

Is there a setting to make the "details" view the default instead of 
"summary"?
I looked in the defaults.inc.php and didn't find anything related to 
that feature.