[gnome-documents] preview: add prev/back navigation with Left and Right keys

[Cosimo Cecchi <cosimoc src gnome org>]

commit 0ec5cf5b302497b6f51d6e741e9f640cdc4b48c7
Author: Alessandro Campagni <alessandro campagni gmail com>
Date:   Mon Apr 29 19:57:53 2013 +0200

    preview: add prev/back navigation with Left and Right keys
    
    https://bugzilla.gnome.org/show_bug.cgi?id=696836

 src/preview.js |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)
---
diff --git a/src/preview.js b/src/preview.js
index 920f007..c4fd463 100644
--- a/src/preview.js
+++ b/src/preview.js
@@ -394,15 +394,18 @@ const PreviewView = new Lang.Class({
     _onKeyPressEvent: function(widget, event) {
         let keyval = event.get_keyval()[1];
         let state = event.get_state()[1];
+        let def_mod_mask = Gtk.accelerator_get_default_mod_mask();
 
-        if ((keyval == Gdk.KEY_Page_Up) &&
-            ((state & Gdk.ModifierType.CONTROL_MASK) != 0)) {
+        if (((keyval == Gdk.KEY_Page_Up) &&
+            ((state & Gdk.ModifierType.CONTROL_MASK) != 0)) ||
+            ((keyval == Gdk.KEY_Left) && ((state & def_mod_mask) == 0))) {
             this.view.previous_page();
             return true;
         }
 
-        if ((keyval == Gdk.KEY_Page_Down) &&
-            ((state & Gdk.ModifierType.CONTROL_MASK) != 0)) {
+        if (((keyval == Gdk.KEY_Page_Down) &&
+            ((state & Gdk.ModifierType.CONTROL_MASK) != 0)) ||
+            ((keyval == Gdk.KEY_Right) && ((state & def_mod_mask) == 0))) {
             this.view.next_page();
             return true;
         }