Created Multihead setup with X11 backend (markdown)

Multihead-setup-with-X11-backend.md

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+**This setup is not recommended. If at all possible, do not run sway this way as features may not work or behave unexpectedly.**
+
+This guide explains how to set up sway running under X11 (e.g. started from an X11 login manager) on multiple monitors.
+
+1. Set up your xorg.conf such that your monitors are presented as a unified screen (e.g. using Xinerama or TwinView). Make sure the ordering corresponds to what you actually want.
+
+2. Start sway with `WLR_X11_OUTPUTS` set to the number of monitors, e.g. `WLR_X11_OUTPUTS=2 sway`
+
+3. Use `DISPLAY=:0 xdotool search --name ''` to get all window ids in the underlying X11 screen. Then use `DISPLAY=:0 xdotool getwindowname <window-id>` to figure out which of the windows is which sway output. You want windows with a name like `wlroots - X11-n`, where `n` is the number of the output.
+
+4. Move the sway outputs to the correct location on the X11 screen with xdotool. E.g. for two monitors with 1920x1080 resolution, do `DISPLAY=:0 xdotool windowmove <window-id-1> 0 0; DISPLAY=:0 xdotool windowmove <window-id-2> 1920 0`
+
+5. Configure the correct resolution for all your outputs in your sway config.
+
+I have created a script to automate steps 3 and 4 for two outputs with a width of 1920 pixels:
+
+`#!/bin/bash
+windows=$(DISPLAY=:0 xdotool search --name '')
+win1=''
+win2=''
+for win in $windows
+do
+    name=$(DISPLAY=:0 xdotool getwindowname $win)
+    if [[ $name == "wlroots - X11-1" ]]
+    then
+        win1=$win
+    elif [[ $name == "wlroots - X11-2" ]]
+    then
+        win2=$win
+    fi
+done
+DISPLAY=:0 xdotool windowmove $win1 1920 0
+DISPLAY=:0 xdotool windowmove $win2 0 0`