[clutter/clutter-1.22] Document CLUTTER_BACKEND and CLUTTER_INPUT_BACKEND envvars

[Emmanuele Bassi <ebassi src gnome org>]

commit b5c8dae5a7cacaebf3639df56dc9bfacfac94976
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Mon Dec 15 17:10:33 2014 +0000

    Document CLUTTER_BACKEND and CLUTTER_INPUT_BACKEND envvars
    
    The allowed values are determined at configure time, but we can list all
    the possible values, and assume people will actually check.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=681300

 doc/reference/clutter/running-clutter.xml |   38 +++++++++++++++++++++++++++++
 1 files changed, 38 insertions(+), 0 deletions(-)
---
diff --git a/doc/reference/clutter/running-clutter.xml b/doc/reference/clutter/running-clutter.xml
index 9d1dc63..0811744 100644
--- a/doc/reference/clutter/running-clutter.xml
+++ b/doc/reference/clutter/running-clutter.xml
@@ -27,6 +27,44 @@
 
       <variablelist>
         <varlistentry>
+          <term>CLUTTER_BACKEND</term>
+          <listitem>
+            <para>Changes the windowing system backend used by Clutter.
+            The allowed values for this environment variable depend on
+            the configuration options used when compiling Clutter. The
+            available values are:</para>
+            <itemizedlist>
+              <listitem><simpara>x11, for the X11 backend</simpara></listitem>
+              <listitem><simpara>wayland, for the Wayland backend</simpara></listitem>
+              <listitem><simpara>win32, for the Windows backend</simpara></listitem>
+              <listitem><simpara>osx, for the MacOS X backend</simpara></listitem>
+              <listitem><simpara>gsk, for the GDK backend</simpara></listitem>
+              <listitem><simpara>eglnative, for the EGL/KMS backend</simpara></listitem>
+              <listitem><simpara>cex100, for the CEx100 backend</simpara></listitem>
+            </itemizedlist>
+            <para>All of the above options except for the <varname>eglnative</varname>
+            and <varname>cex100</varname> backends also have an input backend.</para>
+          </listitem>
+        </varlistentry>
+        <varlistentry>
+          <term>CLUTTER_INPUT_BACKEND</term>
+          <listitem>
+            <para>Changes the input backend used by Clutter.
+            The allowed values for this environment variable depend on
+            the configuration options used when compiling Clutter. The
+            available values are:</para>
+            <itemizedlist>
+              <listitem><simpara>tslib</simpara></listitem>
+              <listitem><simpara>evdev</simpara></listitem>
+              <listitem><simpara>null</simpara></listitem>
+            </itemizedlist>
+            <para>This environment variable is only useful for setting the input
+            backend when using a windowing system backend that does not have an
+            input API, like the <varname>eglnative</varname> or the <varname>cex100</varname>
+            windowing system backends.</para>
+          </listitem>
+        </varlistentry>
+        <varlistentry>
           <term>CLUTTER_SCALE</term>
           <listitem>
             <para>Forces the window scaling factor to that value