Unity actually provides the feature "fadetodesktop".
This change is needed to make unityshell just conflict with the Compiz "Fade to Desktop" (fadedesktop) plug-in, but work together with "Show Desktop" (showdesktop).
showdesktop only works if it is started after unityshell.. Fixes: https://bugs.launchpad.net/bugs/1067534. Approved by Marco Trevisan (Treviño).