With xfce4-settings installed, current mode of monitor is not preserved on disconnection, so when the monitor is connected again, it will simply be in "off" state. It does not kill X or xfce though, so `xrandr --output OUTPUT --auto`, for example, makes the monitor lights up again and nothing is lost. Without xfce4-settings installed, this problem does not occur. Unlike VGA and DVI, for HDMI and DP connection, powering off the monitor (but not DPMS off) is equivalent to disconnection, so this would be quite a problem for those prefer to do that when the monitor is not needed or when they are away. Attached is a debug log produced by the command here: http://docs.xfce.org/xfce/xfce4-settings/xfsettingsd Also compare the two sets of xrandr outputs; They are produced by running `xrandr` after disconnection and reconnection of the monitor with(out) xfce4-settings installed.
Created attachment 6443 XFSETTINGSD_DEBUG=1 xfsettingsd --replace --no-daemon
Created attachment 6444 xrandr outputs without xfce4-settings installed
Created attachment 6445 xrandr outputs with xfce4-settings installed
Created attachment 6446 xrandr outputs without xfce4-settings installed
*** Bug 12219 has been marked as a duplicate of this bug. ***
I also duplicate this problem in a single monitor configuration with an hdmi interface using the xfce spin of Fedora 23. I notice that the problem also occurs in Fedora 22, however Fedora 21 operates normally. That puts some time boundaries around when this regression slipped in. Unfortunately my Seiki 39" monitor insists on powering down after a few hours of non use, so the problem is especially annoying. Thanks Tom Yan for the workaround hint about xrandr --output HDMI-0 --auto. I've set up a screen session in the context of the xfce environment, then ssh into that screen session and run the xrandr command. That workaround restores signal to the monitor and nothing is lost. It's a bit ugly, but at least we have a workaround.
I just use an xfce launcher that does: xfsettingsd --replace and when my monitor configuration gets screwed up when my tv monitor gets powered on, I just click the launcher that runs: xfsettingsd --replace and my original monitor settings are restored. jack
This bug seems replated: https://bugzilla.xfce.org/show_bug.cgi?id=12430
Does #11107 (available in xfce4-settings 4.12.1) fix your issue ?
I haven't tested but almost sure that it fixes, may be closed
Closing, thank you.