I've tried all combinations of styling that I can think of. The tabNavigator styles as I would like in Flex 3. Since the control is still in the mx namespace in Flash Builder, I would have expected the styles created in 3 to carry over (as long as I namespaced the control in the CSS file). However, no matter what I do, I'm unable to skin the button part of the tab navigator. I'm using a recent nighly build where the namespace has changed to mx rather than halo. Has anyone run into this?