last fix won't actually work. it's too early.

xpfe/appshell/src/nsAppShellService.cpp

@@ -282,14 +282,12 @@ void nsAppShellService::CreateHiddenWindow()
   nsresult rv;
   nsIURI* url = nsnull;
 
-#if 0 // temporary until the right NECKO thing is figured out
 #ifndef NECKO
   rv = NS_NewURL(&url, "chrome://navigator/content/hiddenWindow.xul");
 #else
-  rv = NS_NewURI(&url, "chrome://navigator/content/hiddenWindow.xul");
+  // rv = NS_NewURI(&url, "chrome://navigator/content/hiddenWindow.xul");
+  return; // temporary stopgap fix
 #endif
-#else
-  rv = NS_ERROR_FAILURE;
   if (NS_SUCCEEDED(rv)) {
     nsCOMPtr<nsIWebShellWindow> newWindow;
     rv = JustCreateTopWindow(nsnull, url, PR_FALSE, getter_AddRefs(newWindow),
@@ -301,7 +299,6 @@ void nsAppShellService::CreateHiddenWindow()
     NS_RELEASE(url);
   }
   NS_ASSERTION(NS_SUCCEEDED(rv), "HiddenWindow not created");
-#endif
 }
 
 // Apply function (Initialize/Shutdown) to each app shell component.