Catch another place were MessageBox.Show was used

StyletIntegrationTests/Bootstrapper.cs

@@ -17,7 +17,7 @@ namespace StyletIntegrationTests
             var message = e.Exception.Message;
             if (e.Exception is TargetInvocationException)
                 message = e.Exception.InnerException.Message;
-            MessageBox.Show(String.Format("Unhandled Exception: {0}", message));
+            IoC.Get<IWindowManager>().ShowMessageBox(String.Format("Unhandled Exception: {0}", message));
             e.Handled = true;
         }
     }