[gnome-shell] Don't create multiple copies of the (+) button

[Adel Gadllah <agadllah src gnome org>]

commit 6a8b50cb000bab39293d0f69a93bc5dce1c7934d
Author: Adel Gadllah <adel gadllah gmail com>
Date:   Mon Oct 5 18:21:51 2009 +0200

    Don't create multiple copies of the (+) button
    
    Currently we recreate it every time Main.overview.show() is called,
     so destroy it to avoid having multiple copies floating around.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=597309

 js/ui/overview.js |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/js/ui/overview.js b/js/ui/overview.js
index 4d5b37c..5f331a4 100644
--- a/js/ui/overview.js
+++ b/js/ui/overview.js
@@ -357,6 +357,10 @@ Overview.prototype = {
             this._activeDisplayPane.close();
         this._workspaces.hide();
 
+        this._addButton.actor.destroy();
+        this._addButton.actor = null;
+        this._addButton = null;
+
         // Create a zoom in effect by transforming the Overview group so that
         // the active workspace fills up the whole screen. The opposite
         // transition is used in show().