[gnome-shell] Revert "screenShield: Connect to the actor's show signal instead of using BEFORE_REDRAW"

[Ray Strode <halfline src gnome org>]

commit 599f2f43e3bdc08bfbd69d1904944f100b0d5af0
Author: Ray Strode <rstrode redhat com>
Date:   Wed Oct 24 10:17:43 2012 -0400

    Revert "screenShield: Connect to the actor's show signal instead of using BEFORE_REDRAW"
    
    This reverts commit bdeb7d86b649cfacfa3f706daac3c78b74f012f4.
    
    git bz PEBKAC

 js/ui/screenShield.js |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)
---
diff --git a/js/ui/screenShield.js b/js/ui/screenShield.js
index 4d60f71..2069568 100644
--- a/js/ui/screenShield.js
+++ b/js/ui/screenShield.js
@@ -580,14 +580,13 @@ const ScreenShield = new Lang.Class({
     showDialog: function() {
         // Ensure that the stage window is mapped, before taking a grab
         // otherwise X errors out
-        let actorShownId = 0;
-        actorShownId = this.actor.connect('show', Lang.bind(this, function() {
+        Meta.later_add(Meta.LaterType.BEFORE_REDRAW, Lang.bind(this, function() {
             if (!this._isModal) {
                 Main.pushModal(this.actor);
                 this._isModal = true;
             }
 
-            this.actor.disconnect(actorShownId);
+            return false;
         }));
 
         this.actor.show();