Backported from X.org's Xserver:

    commit 6b5978dcf1f7ac3ecc2f22df06f7000f360e2066
    Author: Richard Hughes <richard@hughsie.com>
    Date:   Mon Aug 17 09:15:32 2009 +0100

        Do not reset lastDeviceEventTime when we do dixSaveScreens

        When we turn off DPMS with DPMSModeOff and do dixSaveScreens, don't reset the
        event time else session clients using IDLETIME will be reset.
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Backported-to-NX-by: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>