[gnome-shell-extensions] alternate-tab: don't assume that at least two windows exist

[Giovanni Campagna <gcampagna src gnome org>]

commit 45da997dd376eae2a529aa8683b3b4e028c9e7f8
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Mon Aug 27 14:25:01 2012 +0200

    alternate-tab: don't assume that at least two windows exist
    
    Initial selection would go out of the array bounds if only one window
    existed.

 extensions/alternate-tab/extension.js |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/extensions/alternate-tab/extension.js b/extensions/alternate-tab/extension.js
index c37a594..232b8c7 100644
--- a/extensions/alternate-tab/extension.js
+++ b/extensions/alternate-tab/extension.js
@@ -149,10 +149,11 @@ const AltTabPopup = new Lang.Class({
         this._appSwitcher.connect('item-entered', Lang.bind(this, this._windowEntered));
 
         // make the initial selection
+	this._currentWindow = 0;
         if (backward)
-            this._select(windows.length - 1);
+            this._select(this._previousWindow());
         else
-            this._select(1);
+            this._select(this._nextWindow());
 
         this.actor.opacity = 0;
         this.actor.show();