refactor: move nixos-manual to reference/ + graphifyignore

reference/nixos-manual/configuration/xfce.chapter.md

@@ -0,0 +1,61 @@
+# Xfce Desktop Environment {#sec-xfce}
+
+To enable the Xfce Desktop Environment, set
+
+```nix
+{
+  services.xserver.desktopManager.xfce.enable = true;
+  services.displayManager.defaultSession = "xfce";
+}
+```
+
+Optionally, *picom* can be enabled for nice graphical effects, some
+example settings:
+
+```nix
+{
+  services.picom = {
+    enable = true;
+    fade = true;
+    inactiveOpacity = 0.9;
+    shadow = true;
+    fadeDelta = 4;
+  };
+}
+```
+
+Some Xfce programs are not installed automatically. To install them
+manually (system wide), put them into your
+[](#opt-environment.systemPackages) from `pkgs.xfce`.
+
+## Thunar {#sec-xfce-thunar-plugins}
+
+Thunar (the Xfce file manager) is automatically enabled when Xfce is
+enabled. To enable Thunar without enabling Xfce, use the configuration
+option [](#opt-programs.thunar.enable) instead of adding
+`pkgs.xfce.thunar` to [](#opt-environment.systemPackages).
+
+If you'd like to add extra plugins to Thunar, add them to
+[](#opt-programs.thunar.plugins). You shouldn't just add them to
+[](#opt-environment.systemPackages).
+
+## Troubleshooting {#sec-xfce-troubleshooting}
+
+Even after enabling udisks2, volume management might not work. Thunar
+and/or the desktop takes time to show up. Thunar will spit out this kind
+of message on start (look at `journalctl --user -b`).
+
+```plain
+Thunar:2410): GVFS-RemoteVolumeMonitor-WARNING **: remote volume monitor with dbus name org.gtk.Private.UDisks2VolumeMonitor is not supported
+```
+
+This is caused by some needed GNOME services not running. This is all
+fixed by enabling "Launch GNOME services on startup" in the Advanced
+tab of the Session and Startup settings panel. Alternatively, you can
+run this command to do the same thing.
+
+```ShellSession
+$ xfconf-query -c xfce4-session -p /compat/LaunchGNOME -s true
+```
+
+It is necessary to log out and log in again for this to take effect.