[gsettings-desktop-schemas] schemas: Add tertiary-button-action for Wacom styli

[Carlos Garnacho <carlosg src gnome org>]

commit b2b911433943ed31e7455347451a12d1a3bc137a
Author: Jason Gerecke <killertofu gmail com>
Date:   Mon Oct 9 14:43:45 2017 -0700

    schemas: Add tertiary-button-action for Wacom styli
    
    https://bugzilla.gnome.org/show_bug.cgi?id=790028

 .../org.gnome.desktop.peripherals.gschema.xml.in   |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/schemas/org.gnome.desktop.peripherals.gschema.xml.in 
b/schemas/org.gnome.desktop.peripherals.gschema.xml.in
index 54d29d9..0f96982 100644
--- a/schemas/org.gnome.desktop.peripherals.gschema.xml.in
+++ b/schemas/org.gnome.desktop.peripherals.gschema.xml.in
@@ -149,6 +149,11 @@
       <summary>Secondary button action</summary>
       <description>Secondary stylus button action, this button is located along the pen handle on some styli 
like the Grip Pen. Other styli like the Airbrush Pen or the Inking Pen only have one button, this setting is 
ineffective on those.</description>
     </key>
+    <key name="tertiary-button-action" enum="org.gnome.desktop.GDesktopStylusButtonAction">
+      <default>'default'</default>
+      <summary>Tertiary button action</summary>
+      <description>Tertiary stylus button action, this button is located along the pen handle on some styli 
like the 3D Pen. Other styli like the Grip Pen only have two buttons, this setting is ineffective on 
those.</description>
+    </key>
   </schema>
   <schema id="org.gnome.desktop.peripherals.tablet.pad-button">
     <key name="action" enum="org.gnome.desktop.GDesktopPadButtonAction">