[gnome-settings-daemon/wip/xsettings-manager] xsettings: add README.xsettings about overrides

[Ryan Lortie <ryanl src gnome org>]

commit 466e08da43f6bf6369074651afc9601c7a00ca32
Author: Ryan Lortie <desrt desrt ca>
Date:   Fri Mar 9 13:08:16 2012 -0500

    xsettings: add README.xsettings about overrides

 plugins/xsettings/Makefile.am      |    1 +
 plugins/xsettings/README.xsettings |   32 ++++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 0 deletions(-)
---
diff --git a/plugins/xsettings/Makefile.am b/plugins/xsettings/Makefile.am
index 5523f75..f457143 100644
--- a/plugins/xsettings/Makefile.am
+++ b/plugins/xsettings/Makefile.am
@@ -88,6 +88,7 @@ plugin_in_files = 		\
 plugin_DATA = $(plugin_in_files:.gnome-settings-plugin.in=.gnome-settings-plugin)
 
 EXTRA_DIST = 			\
+	README.xsettings	\
 	$(plugin_in_files)	\
 	$(NULL)
 
diff --git a/plugins/xsettings/README.xsettings b/plugins/xsettings/README.xsettings
new file mode 100644
index 0000000..cacc6a2
--- /dev/null
+++ b/plugins/xsettings/README.xsettings
@@ -0,0 +1,32 @@
+This is very simple documentation for the 'override' GSettings key for
+gnome-setting-daemon's xsettings plugin.
+
+The override is given as a dictionary of overrides to be applied on top
+of the usual values that are exported to the X server as XSETTINGS.  The
+intent of this is to allow users to override values of programmatically
+determined settings (such as 'Gtk/ShellShowsAppMenu') and to allow
+developers to introduce new XSETTINGS for testing (without having to kill the
+gnome-settings-daemon running in the session and run their own patched
+version).
+
+The type of the overrides is 'a{sv}'.
+
+The key gives the full XSETTINGS setting name to override (for example,
+'Gtk/ShellShowsAppMenu').  The value is one of the following:
+
+ - a string ('s') for the case of a string XSETTING
+
+ - an int32 ('i') for the case of an integer XSETTING
+
+ - a 4-tuple of uint16s ('(qqqq)') for the case of a color XSETTING
+
+Dictionary items with a value that is not one of the above types will be
+ignored.  Specifically note that XSETTINGS does not have a concept of
+booleans -- you must use an integer that is either 0 or 1.
+
+An example setting for this key (as expressed in GVariant text format)
+might be:
+
+ { 'Gtk/ShellShowsAppMenu': < 0 >, 'Xft/DPI', < 96 > }
+
+Noting that variants must be specified in the usual way (wrapped in <>).