title: Display AlertDialog as system overlay window from Service
body: <p>I have issue with displaying AlertDialog from Service. I am able to display custom layout window using Toast or using WindowManager(TYPE_SYSTEM_ALERT or TYPE_SYSTEM_OVERLAY). But, I do not want to use custom layout, I prefer to use nice AlertDialog GUI directly.</p>
  
  <p>Scenario:</p>
  
  <ul>
  <li>Running Service. No active Activity present.</li>
  <li>On some external event, Service sends Notification</li>
  <li>When user press Notification, Service is informed via PendingIntent and AlertDialog should be displayed (created with <code>AlertDialog.Builder(this)</code>)</li>
  </ul>
  
  <p>Error:</p>
  
  <pre><code>ERROR/AndroidRuntime(1063): Caused by: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
  </code></pre>
  
  <p>Searching for the answer lead me to impression that I am trying something that is currently not possible (Android 2.2). Or maybe it is.</p>