Thread:Extension talk:Header Tabs/Header Tabs 0.8 not fully compatible with Mediawiki 1.17?/reply

There's some additions to add to your css file on this very page, that fixed the same problem on my installation.

"Useful CSS for Overriding jQueryUI style"

Also, I can't remember if these css fixes, or installing MW 1.18 brought back the hover-sensitive light blue tabs.