--- a/accessible/tests/mochitest/tree/test_tabbrowser.xul
+++ b/accessible/tests/mochitest/tree/test_tabbrowser.xul
@@ -51,34 +51,34 @@
         onStateChange: function onStateChange(aWebProgress,
                                               aRequest,
                                               aStateFlags,
                                               aStatus)
         {
           if (aStateFlags & Ci.nsIWebProgressListener.STATE_STOP) {
             tabBrowser.removeProgressListener(progressListener);
 
-            testAccTree();
+            SimpleTest.executeSoon(testAccTree);
           }
         }
       };
       tabBrowser.addProgressListener(progressListener,
                                      Ci.nsIWebProgress.NOTIFY_STATE_WINDOW);
 
       // Test XUL and HTML documents.
       tabBrowser.loadTabs(["about:", "about:mozilla"], false, true);
     }
 
     function testAccTree()
     {
       var tabBrowser = document.getElementById("tabbrowser");
 
-      //////////
+      ////////////////////
       // Tab bar
-      //////////
+      ////////////////////
       var tabsAccTree = {
         // xul:tabs
         role: ROLE_PAGETABLIST,
         children: [
           // Children depend on application (UI): see below.
         ]
       };
 
@@ -155,19 +155,19 @@
           // "List all tabs" dropdown
           // XXX: This child(?) is not present in this test.
           //      I'm not sure why (though probably expected).
           );
       }
 
       testAccessibleTree(tabBrowser.tabContainer, tabsAccTree);
 
-      //////////
+      ////////////////////
       // Tab contents
-      //////////
+      ////////////////////
       var tabboxAccTree = {
         // xul:tabpanels
         role: ROLE_PANE,
         children: [
           {
             // xul:notificationbox
             role: ROLE_PROPERTYPAGE,
             children: [