Comment 9 for bug 1672033

xrandr output in rootless session:

igor:~% ps aux | grep Xorg
igor 3779 3.2 0.0 199348 51332 tty3 S+ 15:49 0:00 /usr/lib/xorg/Xorg vt3 -displayfd 3 -auth /run/user/1000/gdm/Xauthority -background none -noreset -keeptty -verbose 3

igor:~% xrandr -q
Screen 0: minimum 8 x 8, current 1920 x 1200, maximum 32767 x 32767
DVI-D-0 connected primary 1920x1200+0+0 (normal left inverted right x axis y axis) 518mm x 324mm
   1920x1200 59.95*+
   1920x1080 60.00
   1680x1050 59.95
   1600x1200 60.00
   1280x1024 60.02
   1280x960 60.00
   1024x768 60.00
   800x600 60.32
   640x480 59.94
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
DP-4 disconnected (normal left inverted right x axis y axis)
DP-5 disconnected (normal left inverted right x axis y axis)

lightdm works, because it starts Xorg as root for itself, which causes monitor initialization and consequently later started rootless session work fine.