diff -r 000000000000 -r 6474c204b198 toolkit/components/prompts/test/prompt_common.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/components/prompts/test/prompt_common.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,123 @@
+const Ci = SpecialPowers.Ci;
+const Cc = SpecialPowers.Cc;
+ok(Ci != null, "Access Ci");
+ok(Cc != null, "Access Cc");
+
+var didDialog;
+
+var isSelectDialog = false;
+var isTabModal = false;
+var usePromptService = true;
+
+var timer; // keep in outer scope so it's not GC'd before firing
+function startCallbackTimer() {
+    didDialog = false;
+
+    // Delay before the callback twiddles the prompt.
+    const dialogDelay = 10;
+
+    // Use a timer to invoke a callback to twiddle the authentication dialog
+    timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+    timer.init(observer, dialogDelay, Ci.nsITimer.TYPE_ONE_SHOT);
+}
+
+
+var observer = {
+    QueryInterface : function (iid) {
+        const interfaces = [Ci.nsIObserver,
+                            Ci.nsISupports, Ci.nsISupportsWeakReference];
+
+        if (!interfaces.some( function(v) { return iid.equals(v) } ))
+            throw SpecialPowers.Cr.NS_ERROR_NO_INTERFACE;
+        return this;
+    },
+
+    observe : SpecialPowers.wrapCallback(function (subject, topic, data) {
+      try {
+        if (isTabModal) {
+          var promptBox = getTabModalPromptBox(window);
+          ok(promptBox, "got tabmodal promptbox");
+          var prompts = SpecialPowers.wrap(promptBox).listPrompts();
+          if (prompts.length)
+              handleDialog(prompts[0].Dialog.ui, testNum);
+          else
+              startCallbackTimer(); // try again in a bit
+        } else {
+          var doc = getDialogDoc();
+          if (isSelectDialog && doc)
+              handleDialog(doc, testNum);
+          else if (doc)
+              handleDialog(doc.defaultView.Dialog.ui, testNum);
+          else
+              startCallbackTimer(); // try again in a bit
+        }
+      } catch (e) {
+        ok(false, "Exception thrown in the timer callback: " + e + " at " + (e.fileName || e.filename) + ":" + (e.lineNumber || e.linenumber));
+      }
+    })
+};
+
+function getTabModalPromptBox(domWin) {
+    var promptBox = null;
+
+    // Given a content DOM window, returns the chrome window it's in.
+    function getChromeWindow(aWindow) {
+        var chromeWin = SpecialPowers.wrap(aWindow).QueryInterface(Ci.nsIInterfaceRequestor)
+                               .getInterface(Ci.nsIWebNavigation)
+                               .QueryInterface(Ci.nsIDocShell)
+                               .chromeEventHandler.ownerDocument.defaultView;
+        return chromeWin;
+    }
+
+    try {
+        // Get the topmost window, in case we're in a frame.
+        var promptWin = domWin.top;
+
+        // Get the chrome window for the content window we're using.
+        var chromeWin = getChromeWindow(promptWin);
+
+        if (chromeWin.getTabModalPromptBox)
+            promptBox = chromeWin.getTabModalPromptBox(promptWin);
+    } catch (e) {
+        // If any errors happen, just assume no tabmodal prompter.
+    }
+
+    // Callers get confused by a wrapped promptBox here.
+    return SpecialPowers.unwrap(promptBox);
+}
+
+function getDialogDoc() {
+  // Trudge through all the open windows, until we find the one
+  // that has either commonDialog.xul or selectDialog.xul loaded.
+  var wm = Cc["@mozilla.org/appshell/window-mediator;1"].
+           getService(Ci.nsIWindowMediator);
+  //var enumerator = wm.getEnumerator("navigator:browser");
+  var enumerator = wm.getXULWindowEnumerator(null);
+
+  while (enumerator.hasMoreElements()) {
+    var win = enumerator.getNext();
+    var windowDocShell = win.QueryInterface(Ci.nsIXULWindow).docShell;
+
+    var containedDocShells = windowDocShell.getDocShellEnumerator(
+                                      Ci.nsIDocShellTreeItem.typeChrome,
+                                      Ci.nsIDocShell.ENUMERATE_FORWARDS);
+    while (containedDocShells.hasMoreElements()) {
+        // Get the corresponding document for this docshell
+        var childDocShell = containedDocShells.getNext();
+        // We don't want it if it's not done loading.
+        if (childDocShell.busyFlags != Ci.nsIDocShell.BUSY_FLAGS_NONE)
+          continue;
+        var childDoc = childDocShell.QueryInterface(Ci.nsIDocShell)
+                                    .contentViewer
+                                    .DOMDocument;
+
+        //ok(true, "Got window: " + childDoc.location.href);
+        if (childDoc.location.href == "chrome://global/content/commonDialog.xul")
+          return childDoc;
+        if (childDoc.location.href == "chrome://global/content/selectDialog.xul")
+          return childDoc;
+    }
+  }
+
+  return null;
+}