In an external style sheet I have the following:

@namespace controlbars "package.to.controlbars"

controlbars|BottomControlBar
{
  fontFamily: openSansRegular;
  fontSize: 10
}

s|Label
{
  fontFamily: openSansRegular;
  fontSize:14
}

Then in a custom class BottomControlBar that inherits from Group

<s:Group>
  <fx:MetaData>
    [Style(name="fontFamily", type="String", inherit="yes")]
    [Style(name="fontSize", type="uint", inherit="yes")]
  </fx:MetaData>

  <s:Group>
    <s:HGroup>
      <s:Label /> // the label here does not pick up fontFmaily and fontSize from BottomControlBar
    </s:HGroup>
  </s:Group>
</s:Group>