FYI: CVE-2012-5639 was assigned on the oss-security mailing list to the lack of a warning when accessing external file references in LibreOffice
Please see http://seclists.org/oss-sec/2012/q4/453 for the discussion.
Marking this as INVALID - there really isn't a bug report here. We would need what the exact problem is as well as reproducible steps. I quickly reviewed the link you provided - if there is a specific request please put it explicitly on our bug tracker as we don't like having requests on different infra that we just get a link to.
Thanks for your understanding and apologies for the long delay. Also removed "security" as this isn't a bug (it's a feature request) and a feature request isn't a security vulnerability, it's just a request for something additional added.
See <http://whatofhow.wordpress.com/2013/12/02/stealth-mode/> for a feature that has been implemented starting in LO 4.2 to address rhbz#887420 and CVE-2012-5639.