Board Thread:Support Requests - Designing Your Wiki/@comment-25503763-20130606211444/@comment-10688548-20130606224355

Yes, except it looks like Youhavenewmessages is used only in Monobook skin. The Wikia equivalent (that is, the one for the skin that 98% of everyone uses) is MediaWiki:Oasis-notification-youhavenewmessages