[gnome-shell] ScreenShield: fix a typo due to the MetaCursorTracker switch

[Giovanni Campagna <gcampagna src gnome org>]

commit 3e8ab0645bef68a45cc91f99f7b470ae5fe3e3a8
Author: Giovanni Campagna <gcampagn redhat com>
Date:   Thu Sep 12 13:04:47 2013 +0200

    ScreenShield: fix a typo due to the MetaCursorTracker switch
    
    And replace another show_cursor() usage with the new API.
    
    Reviewed-by: Carlos Soriano in IRC.

 js/ui/screenShield.js |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/js/ui/screenShield.js b/js/ui/screenShield.js
index e5ba2de..32fd737 100644
--- a/js/ui/screenShield.js
+++ b/js/ui/screenShield.js
@@ -1087,15 +1087,15 @@ const ScreenShield = new Lang.Class({
 
         this._checkArrowAnimation();
 
-        let motionId = global.stage.connect('captured-event', function(stage, event) {
+        let motionId = global.stage.connect('captured-event', Lang.bind(this, function(stage, event) {
             if (event.type() == Clutter.EventType.MOTION) {
-                global.stage.show_cursor();
+                this._cursorTracker.set_pointer_visible(true);
                 global.stage.disconnect(motionId);
             }
 
             return false;
-        });
-        this._cursorTracker.set_pointer_tracker(false);
+        }));
+        this._cursorTracker.set_pointer_visible(false);
 
         this._lockScreenState = MessageTray.State.SHOWN;
         this._lockScreenGroup.fixed_position_set = false;