nixpkgs/nixos/doc/manual/configuration/xfce.xml

<chapter xmlns="http://docbook.org/ns/docbook"
         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         version="5.0"
         xml:id="sec-xfce">
 <title>Xfce Desktop Environment</title>
 <para>
  To enable the Xfce Desktop Environment, set
<programlisting>
<xref linkend="opt-services.xserver.desktopManager.xfce.enable" /> = true;
<xref linkend="opt-services.xserver.displayManager.defaultSession" /> = "xfce";
</programlisting>
 </para>
 <para>
  Optionally, <emphasis>picom</emphasis> can be enabled for nice graphical
  effects, some example settings:
<programlisting>
<link linkend="opt-services.picom.enable">services.picom</link> = {
  <link linkend="opt-services.picom.enable">enable</link> = true;
  <link linkend="opt-services.picom.fade">fade</link> = true;
  <link linkend="opt-services.picom.inactiveOpacity">inactiveOpacity</link> = 0.9;
  <link linkend="opt-services.picom.shadow">shadow</link> = true;
  <link linkend="opt-services.picom.fadeDelta">fadeDelta</link> = 4;
};
</programlisting>
 </para>
 <para>
  Some Xfce programs are not installed automatically. To install them manually
  (system wide), put them into your
  <xref linkend="opt-environment.systemPackages"/> from <literal>pkgs.xfce</literal>.
 </para>
 <simplesect xml:id="sec-xfce-thunar-plugins">
  <title>Thunar Plugins</title>
  <para>
    If you'd like to add extra plugins to Thunar, add them to
    <xref linkend="opt-services.xserver.desktopManager.xfce.thunarPlugins"/>.
    You shouldn't just add them to <xref linkend="opt-environment.systemPackages"/>.
  </para>
 </simplesect>
 <simplesect xml:id="sec-xfce-troubleshooting">
  <title>Troubleshooting</title>
  <para>
   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 <command>journalctl --user -b</command>).
<programlisting>
Thunar:2410): GVFS-RemoteVolumeMonitor-WARNING **: remote volume monitor with dbus name org.gtk.Private.UDisks2VolumeMonitor is not supported
</programlisting>
   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.
<programlisting>
<prompt>$ </prompt>xfconf-query -c xfce4-session -p /compat/LaunchGNOME -s true
</programlisting>
   A log-out and re-log will be needed for this to take effect.
  </para>
 </simplesect>
</chapter>