--- a/x.rst	Mon Oct 27 18:44:13 2014 +0200
+++ b/x.rst	Sun Nov 02 16:48:07 2014 +0200
@@ -414,3 +414,18 @@
                 Mesa is an open source 3D computer graphics library that
                 provides a generic OpenGL implementation for rendering
                 three-dimensional graphics on multiple platforms.
+
+Running a secondary X server.
+=============================
+::
+
+  $ startx xterm -- :1 -depth 16
+
+In order to fix::
+
+  X: user not authorized to run the X server
+
+run::
+
+  $ sudo dpkg-reconfigure x11-common
+