separate xorg and i3

modules/desktop/i3.nix

@@ -0,0 +1,5 @@
+{ ... }: {
+
+  services.xserver.windowManager = { i3 = { enable = true; }; };
+
+}

modules/desktop/xorg.nix

@@ -0,0 +1,53 @@
+{ pkgs, ... }: {
+
+  # Enable the X11 windowing system.
+  services.xserver = {
+    enable = true;
+
+    # Enable touchpad support
+    libinput.enable = true;
+
+    # Disable mouse acceleration
+    libinput.mouse.accelProfile = "flat";
+    libinput.mouse.accelSpeed = "1.15";
+
+    # Keyboard responsiveness
+    autoRepeatDelay = 250;
+    autoRepeatInterval = 40;
+
+    # Configure keymap in X11
+    layout = "us";
+    xkbOptions = "eurosign:e,caps:swapescape";
+
+    # Login screen
+    displayManager = {
+      lightdm = {
+        enable = true;
+
+        # Make the login screen dark
+        greeters.gtk.theme.name = "Adwaita-dark";
+
+        # Put the login screen on the left monitor
+        greeters.gtk.extraConfig = ''
+          active-monitor=0
+        '';
+      };
+      setupCommands = ''
+        ${pkgs.xorg.xrandr}/bin/xrandr --output DisplayPort-0 \
+                                            --mode 1920x1200 \
+                                            --pos 1920x0 \
+                                            --rotate left \
+                                        --output HDMI-0 \
+                                            --primary \
+                                            --mode 1920x1080 \
+                                            --pos 0x559 \
+                                            --rotate normal \
+                                        --output DVI-0 --off \
+                                        --output DVI-1 --off \
+      '';
+    };
+
+  };
+
+}
+