Can't help directly, but have you experimented in the Style Explorer?
It makes styling anything much easier, especially TabNavigator.
Thank you for pointing me to that link, I am sure I will get a lot of use out of it. However, it didn't solve my issue. The text in the tabs in the style sandbox are all vertically aligned in the middle, which is what I am trying to accomplish. However, in my application, they are all vertically aligned top, and there seems to be no option to change the vertical alignment.
Thats odd behavior because the default of the tab navigator is to vertical align to center. Perhaps there is something in your css that is causing a problem. Here is a quick example with an inline style where the tabs are vertical align to center. If you problems continue please post your css definitions.
<!-- dpcontrols/TreeSimple.mxml -->
<mx:Canvas width="356" height="307">
<mx:TabNavigator top="60" bottom="20" left="20" right="20">
<mx:Canvas label="Tab1" width="100%" height="100%">
<mx:Canvas label="Tab2" width="100%" height="100%">
I've narrowed it down to an issue with embeded fonts. When I remove the embeded fonts, everything lines up as it is supposed to. However, when I add the embeded fonts back, everything becomes top aligned.