[gnome-shell] system: Hide the AltSwitcher when we have nothing to show

[Jasper St. Pierre <jstpierre src gnome org>]

commit f0da08bbb19705da6163c1f10195e260d0bb07ba
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Mon Aug 26 15:21:23 2013 -0400

    system: Hide the AltSwitcher when we have nothing to show
    
    https://bugzilla.gnome.org/show_bug.cgi?id=706852

 js/ui/status/system.js |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/js/ui/status/system.js b/js/ui/status/system.js
index 40968ab..c319b09 100644
--- a/js/ui/status/system.js
+++ b/js/ui/status/system.js
@@ -60,6 +60,8 @@ const AltSwitcher = new Lang.Class({
             // sync the pointer to make sure they update.
             global.sync_pointer();
         }
+
+        this.actor.visible = (childToShow != null);
     },
 
     _onDestroy: function() {