title: Show an AlertDialog from a background Thread with the appcontext
body: <p>Is possible to raise an AlertDialog from a background thread using a reference to getApplicationContext()?</p>
  
  <p>I'm trying with that code but it doesn't work</p>
  
  <pre><code>    new Thread(){
          public void run(){
              new AlertDialog.Builder(appcontext)
              .setMessage("Test")
              .setPositiveButton("Ok", null)
              .show();
          }
      }.start();
  </code></pre>
  
  <p>Thanks in advance</p>