Comment 5 for bug 1052481

What has to be done is simply adding something like:

.nautilus-inactive-pane .view {
 background-color: shade (@bg_color, 0.8);
}

in the gtk-3.0/apps/nautilus.css file for the Ambiance theme. Varying the coefficient (0.8) will make it lighter/darker. Or we could use another color instead of the default bg_color.

After doing some googling, it seems that the extra pane does not exist in Nautilus 3.6 (https://live.gnome.org/Nautilus/Roadmap/3.6 and there's also a discussion here http://www.omgubuntu.co.uk/2012/08/ubuntu-12-10-may-ship-with-older-but-more-featured-nautilus). Probably this is why the styling was removed from Adwaita trunk. So, we should ask around if Ubuntu plans to stay with 3.4 for raring, otherwise this bug has no relevance.