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I am using Manjaro with XFCE on a laptop (Thinkpad x240). I have a docking station (Thinkpad Ultra Dock) with a monitor connected and that works like a charm. Today, I received my second monitor and as I plugged it in, it just mirrors my first display. There's no setting in XFCE to set it as third monitor (laptop display included).

However, in the settings editor are both display listed (first with HDMI, the second with DP) and the position is set accordingly to the information I found on Google (set the X-position of the second monitor with the resolution of the first monitor, which is 1920).

I changed this setting with xfconf-query -c displays -p /Schemes/Apply -t string -s 'Default' --create

Still no change, even after restart. I tried everything, starting with xrandr --output HDMI1 --left-of DP2 and vice versa.

I also tried arandr (xrandr GUI), and even though both monitor are set in a line in arandr, they just mirror the same desktop.

If you have any ideas how to fix it, please don't hesitate to let me know.

uname -a

Linux bx 3.16.7.3-1-MANJARO #1 SMP PREEMPT Fri Dec 19 18:34:00 UTC 2014 x86_64 GNU/Linux

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Ok guys, here's the problem:

Using the Thinkpad Ultra Dock, all connected displays are internally handled by a Displayport hub. Sadly, Linux can't differante multiple monitors using the Displayport MST hub.

Read it up here: http://www.thinkwiki.org/wiki/ThinkPad_Ultra_Dock

Linux does not yet offer explicit support for the DisplayPort MST hub built into this dock, so multi-screen support is not fully functional under Linux. A single screen works fine and is fully controllable, but multiple screens are handled by a some unconfigurable fallback mode, and appear a single display; they cannot be individually configured in terms of resolution, relative position etc.

However, in regards to my X240 the page says:

On the ThinkPad X240, one way to use two external screens is to attach one to a dock port, and another to the laptop's own mini DisplayPort port.

Which is working fine.

  • Good question and good solution. Head on! – Nils Jan 24 '15 at 22:55

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