private void showDialog() {
  FragmentTransaction ft = getChildFragmentManager().beginTransaction();
  Fragment prev = getFragmentManager().findFragmentByTag("dialog");
  if (prev != null) {
      ft.remove(prev);
  }
  ft.addToBackStack(null);

  // Create and show the dialog.
  WifiListDialogFragment newFragment = WifiListDialogFragment.newInstance();
  newFragment.setTargetFragment(this, REQUEST_CODE_SELECT_WIFI_AP);
  newFragment.show(ft, "dialog");
}