Created attachment 617558 [details] [diff] [review]
On OS X we never need the white background, on Windows we can omit it when using a lightweight theme.
This is still needed on Windows with lightweight themes. Maybe a reduced opacity can help in such cases.
With the default theme on Windows the background of the url container is already white with tabs on top. With tabs on bottom the white identity box looks strange on glass. Reducing the opacity also fixes this case.
Created attachment 617582 [details]
Screenshot with tabs on bottom
On Windows 7 with default theme.