SilverStripe: How do I insert a tab before another tab?

I am tryi开发者_StackOverflow社区ng to insert a new admin tab before Root.Content.Main without any luck. I've tried:

$fields->insertBefore(new Tab('Root.Content.Overview', 'Overview'), 'Root.Content.Main');

and

$fields->addFieldToTab('Root.Content', new Tab('OverviewTab', 'Root.Content.Overview'), 'Root.Content.Main');

without any luck.

Anyone have any ideas? I've hunted through the API but there isn't much explanation as to how the tab naming system works.

Figured it out...

$fields->insertBefore(new Tab('Overview', 'Project Overview'), 'Main');