Comment 14 for bug 1159430

Here are some more thoughts about this. Nautilus 3.8.0 still sets its desktop window to have type _NET_WM_WINDOW_TYPE_DESKTOP. (See set_wmspec_desktop_hint() in nautilus-desktop-window.c.) Since this apparently works fine in GNOME Shell, I can only assume that Mutter allows such windows to be transparent, and to be layered on top of a background below. I tried writing a small test program in C that displays a transparent window. If I modify the program to set the window type to _NET_WM_WINDOW_TYPE_DESKTOP, then in Compiz the window is transparent no more.

One way to work around this might be to patch Nautilus to use a different window type, e.g. _NET_WM_WINDOW_TYPE_NOTIFICATION . Back in the ancient times of GNOME 2 there was a transparent background patch for Nautilus floating around which did exactly that; see http://ubuntuforums.org/showthread.php?t=1699841 . But that seems a bit hacky and would be a futher divergence from the vanilla Nautilus source base. A better approach might be to fix Compiz to allow transparent desktop windows as Mutter apparently does.