Bug 94458: change dynamically registered listeners to "create" and "destroy" events to listen to "popupshowing" and "popuphiding". r=bryner, sr=hyatt

suite/common/permissions/imageContextOverlay.xul

@@ -99,7 +99,7 @@
 
       addContextMenuItemListeners : function (aEvent) {
         var contextPopup = document.getElementById("contentAreaContextSet");
-        contextPopup.addEventListener("create", cookieContextMenu.initImageBlocking, false);
+        contextPopup.addEventListener("popupshowing", cookieContextMenu.initImageBlocking, false);
       }
     }