How to trigger a Dialog from an Application instance?

i'm looking for a way to show a Dialog no matter what activity is shown.

I think what I'm trying to achieve is better explained using some code :

public class MyApp extends Application {

        public 开发者_Python百科MyApplication() {
        }

        @Override
        public void onCreate() {
                super.onCreate();

                boolean success = doSomeWebServiceCall();

                if (!success)
                        showAlertDialog();  // fails with error
        }
}

The error I am getting is :

ERROR/AndroidRuntime(375): Caused by: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
at android.view.ViewRoot.setView(ViewRoot.java:460)

Only an Activity can display a Dialog. Consider using a dialog-themed Activity instead, which can be launched from your Application object via startActivity().

I think a toast (could even throw in an image in this toast) is much more convenient if you don't need user interaction

Toast toast = Toast.makeText(getApplicationContext(), "YOUR TEXT HERE", Toast.LENGTH_LONG);
LinearLayout toastView = (LinearLayout) toast.getView();
ImageView infoImage = new ImageView(getApplicationContext());
infoImage.setImageResource(drawable.your_image);
toastView.addView(infoImage, 0);
toast.show();