title: Disabling and enabling back button
body: <p>In the app i m looking for the users location using gps.In the Async pre execute method i m showing a toast.I want that while i show that toast the back button should be disabled</p>
  
  <p>aftr the location is found i want to enable the back button in the post execute!</p>
  
  <p>to disable the back button i have used.But this is not working</p>
  
  <pre><code> OnKeyListener mainScreenKeyListener = new OnKeyListener() {
                  @Override
                  public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event) {
                      boolean disableEvent = false;
                      if (event.getKeyCode()==KeyEvent.KEYCODE_BACK) {
                          disableEvent = true;
                      }
  
                      return disableEvent;
                  }
              };
  </code></pre>