Thank you for pointing at that code here. I already had put in a
comment that it needs clean up, but never got around to that. I tried
to make the values here consistent with the ones in GSThemeDrawing.
But of course this is only the first step. The values should come from
the theme, to allow themes to have different styles for the tabs and
more importantly, the tab view should be flipped.
We need to clean all that up, but should do so after the release.
Could you please give the new values a try and report back whether
they work for you. I only tested with NSTopTabsBezelBorder, which
should be the most common case.