diff --git a/toolkit/mozapps/downloads/tests/chrome/Makefile.in b/toolkit/mozapps/downloads/tests/chrome/Makefile.in
index d9c750de851..ea5af1dd276 100644
--- a/toolkit/mozapps/downloads/tests/chrome/Makefile.in
+++ b/toolkit/mozapps/downloads/tests/chrome/Makefile.in
@@ -61,6 +61,7 @@ _CHROME_FILES = \
   test_space_key_pauses_resumes.xul \
   test_ui_stays_open_on_alert_clickback.xul \
   test_bug_429247.xul \
+  utils.js \
   $(NULL)
 
 ifneq (,$(filter cocoa, $(MOZ_WIDGET_TOOLKIT)))
diff --git a/toolkit/mozapps/downloads/tests/chrome/test_retention_is_0_closes.xul b/toolkit/mozapps/downloads/tests/chrome/test_retention_is_0_closes.xul
index ade9fdf92ce..04d919f6472 100644
--- a/toolkit/mozapps/downloads/tests/chrome/test_retention_is_0_closes.xul
+++ b/toolkit/mozapps/downloads/tests/chrome/test_retention_is_0_closes.xul
@@ -53,13 +53,21 @@
           src="chrome://mochikit/content/MochiKit/packed.js"/>
   <script type="application/javascript"
           src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript"
+          src="chrome://mochikit/content/chrome/toolkit/mozapps/downloads/tests/chrome/utils.js"/>
 
   <script type="application/javascript">
   <![CDATA[
 
-const Cc = Components.classes;
-const Ci = Components.interfaces;
-const Cr = Components.results;
+function setPref(aDoTest)
+{
+  let prefs = Cc["@mozilla.org/preferences-service;1"].
+              getService(Ci.nsIPrefBranch);
+
+  // If we're testing, set retention to auto-remove and auto-close
+  prefs.setIntPref("browser.download.manager.retention", aDoTest ? 0 : 2);
+  prefs.setBoolPref("browser.download.manager.closeWhenDone", aDoTest);
+}
 
 function bug413093obs()
 {
@@ -70,10 +78,6 @@ bug413093obs.prototype = {
   observe: function(aSubject, aTopic, aData)
   {
     if ("domwindowopened" == aTopic) {
-      let ww = Cc["@mozilla.org/embedcomp/window-watcher;1"].
-               getService(Ci.nsIWindowWatcher);
-      ww.unregisterNotification(this);
-
       // If we opened before we were paused, we need to set up our proper state
       // We also should not try to resume (we weren't paused!)
       if (!this.wasPaused) {
@@ -88,14 +92,22 @@ bug413093obs.prototype = {
       let dm = Cc["@mozilla.org/download-manager;1"].
                 getService(Ci.nsIDownloadManager);
       dm.resumeDownload(this.mDownload.id);
-    } else if ("timer-callback" == aTopic) {
-      this.setPref(false);
+    }
+    else if("domwindowclosed" == aTopic) {
+      let ww = Cc["@mozilla.org/embedcomp/window-watcher;1"].
+               getService(Ci.nsIWindowWatcher);
+      ww.unregisterNotification(this);
 
-      let dmui = Cc["@mozilla.org/download-manager-ui;1"].
-                 getService(Ci.nsIDownloadManagerUI);
-      ok(!dmui.visible, "Download Manager UI is not showing");
+      // Let the UI finish doing whatever it needs to do
+      executeSoon(function() {
+        setPref(false);
 
-      SimpleTest.finish();
+        let dmui = Cc["@mozilla.org/download-manager-ui;1"].
+                   getService(Ci.nsIDownloadManagerUI);
+        ok(!dmui.visible, "Download Manager UI is not showing");
+
+        SimpleTest.finish();
+      });
     }
   },
 
@@ -119,25 +131,12 @@ bug413093obs.prototype = {
                 getService(Ci.nsIDownloadManager);
       dm.removeListener(this);
 
-      // We have to do this on a timer so other JS stuff that handles the UI
-      // can actually catch up to us...
-      let timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
-      timer.init(this, 1000, Ci.nsITimer.TYPE_ONE_SHOT);
+      // If this test is going to pass, we'll get a domwindowclosed notification
     }
   },
   onStateChange: function(a, b, c, d, e) { },
   onProgressChange: function(a, b, c, d, e, f, g) { },
   onSecurityChange: function(a, b, c, d) { },
-
-  setPref: function(aDoTest)
-  {
-    let prefs = Cc["@mozilla.org/preferences-service;1"].
-                getService(Ci.nsIPrefBranch);
-
-    // If we're testing, set retention to auto-remove and auto-close
-    prefs.setIntPref("browser.download.manager.retention", aDoTest ? 0 : 2);
-    prefs.setBoolPref("browser.download.manager.closeWhenDone", aDoTest);
-  }
 };
 function test()
 {
@@ -186,7 +185,7 @@ function test()
 
   let obs = new bug413093obs();
   dm.addListener(obs);
-  obs.setPref(true);
+  setPref(true);
 
   // Start the test when the download manager window loads
   let ww = Cc["@mozilla.org/embedcomp/window-watcher;1"].
diff --git a/toolkit/mozapps/downloads/tests/chrome/utils.js b/toolkit/mozapps/downloads/tests/chrome/utils.js
new file mode 100644
index 00000000000..1895eec2ea7
--- /dev/null
+++ b/toolkit/mozapps/downloads/tests/chrome/utils.js
@@ -0,0 +1,60 @@
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is
+ * Mozilla Corporation.
+ * Portions created by the Initial Developer are Copyright (C) 2008
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Shawn Wilsher <me@shawnwilsher.com> (Original Author)
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+/**
+ * Provides utility functions for the download manager chrome tests.
+ */
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cr = Components.results;
+
+/**
+ * Executes a function shortly after the call, but lets the caller continue
+ * working (or finish).
+ */
+function executeSoon(aFunc)
+{
+  let tm = Cc["@mozilla.org/thread-manager;1"].getService(Ci.nsIThreadManager);
+  
+  tm.mainThread.dispatch({
+    run: function()
+    {
+      aFunc();
+    }
+  }, Ci.nsIThread.DISPATCH_NORMAL);
+}