[gnome-documents] window: go back from preview with GDK_KEY_Back

[Cosimo Cecchi <cosimoc src gnome org>]

commit bfbcdb435796c711f25d26614e1f74e299867596
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Thu Sep 15 08:49:51 2011 -0400

    window: go back from preview with GDK_KEY_Back
    
    As seen e.g. on many Thinkpad laptops.

 src/mainWindow.js |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/mainWindow.js b/src/mainWindow.js
index 439418b..16f25c7 100644
--- a/src/mainWindow.js
+++ b/src/mainWindow.js
@@ -106,7 +106,8 @@ MainWindow.prototype = {
             return true;
         }
 
-        if (keyval == Gdk.KEY_Escape) {
+        if (keyval == Gdk.KEY_Escape ||
+            keyval == Gdk.KEY_Back) {
             Global.modeController.setWindowMode(WindowMode.WindowMode.OVERVIEW);
             return true;
         }