I have two monitors, DP-3 with 2560x1440 resolution, and HDMI-1 with 1920x1200 resolution. I want HDMI-1 to be displayed to the left of DP-3. When I run xrandr --output HDMI-1 --auto --right-of DP-3 everything displays as intended, but when I use --left-of the entirety of what originally displayed on HDMI-1 gets displayed on the DP-3 monitor and the rest of what was originally displayed on DP-3 extends into the monitor of HDMI-1.

There is another thread here from a few years ago where someone was having a similar issue, but the solution posted doesn't work for me. It also is never explained why --left-of apparently messes with scaling.

I don't know if this helps, but I'm using i3 and LightDM as my windowing and display managers

1 Answer 1


First, the issue was not with --left-of but rather which of the two outputs was scaled. xrandr appears to use the unscaled sizes of the displays to decide where to position the output display causing strange behaviour. Assuming you are not scaling either of your outputs, this issue should not apply to you.

I'm a little confused from your description as to what actually happened and unfortunately I haven't used LightDM in many years, but some of the following should be helpful

a) On my machine the monitors don't always refresh correctly after I screw around with xrandr, flipping to another virtual terminal and back fixes it.

b) https://wiki.archlinux.org/title/LightDM#Multiple-monitor_setup gives an example of setting up an xorg.conf file to setup two monitors in LightDM

c) executing xrandr |grep "^[^ ]" will display the size and position of your monitors (without all the other detail). This will let you see where the displays are positioned and may help you figure out what is happening

d) as a last resort you can just position the displays where you want with xrandr --output <display> --pos <X>x<Y> (remember that the axes grow from the top left-hand corner

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