This one seems to be supported by KDE (partially) and XFCE.
On KDE it doesn't inhibit the ScreenSaver, however it's the only
inhibition that appears to be available on XFCE (untested due
to lack of XFCE system at hand).

Change-Id: I4eab04d8ef66fc4fa55f57add46cb1ad15a8e2b3