Update: Using a MiniDisplayPort to HDMI adapter
and xrandr --output HDMI1 --left-of eDP1 --auto,
the image on the external monitor seems to show only parts
of what's there.

Moving the mouse left out and above out of the left/monitor
works -> mouse pointer disappears.

Attached full Xorg.0.log including the part when the new output 
was created.

Attaching a MiniDisplayPort to DVI adapter, no output is detected
by xrandr though (all outputs show disconnected).

Cheers,

Nico

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