This is from wikitech-l (see URL): Extensions like SyntaxHighlight_GeSHi put generated styles or javascript into the page via ParserOutput->mHeadItems. These items should be made available through the API so gadgets like LivePreview can use them.
Version: 1.16.x
Severity: enhancement
URL: http://lists.wikimedia.org/pipermail/wikitech-l/2010-January/046242.html