Comment # 13 on bug 798308 from Koenraad Lelong

Created attachment 657843 [details]
xrandr with dp-monitor attached

This is the output of xrandr --verbose, with a DP-monitor attached.
The monitor is a multi-input monitor : DP, DVI and VGA. I can let it scan for
active sources and it finds no active source, although in
"Systemsettings/Display & monitor" the DP screen is active.
Since the monitor can scan for sources, it's on, or maybe I am missing
something. Also the power LED is blue, indicating it's active. When it's not
active/sleeping the LED is orange.
When I attach a VGA monitor and set this active in "Systemsettings/Display &
monitor" I do get an image on the monitor.
If you like I can send an output of xrandr --verbose when both cables are
attached to the monitor.

Unfortunately, after some testing, at the moment I can't get at the "taskbar".
It seems to be on a display that's not active any more. I will try attaching
the VGA again.