@Override
    public boolean onSupportNavigateUp() {
        if (getSupportFragmentManager().popBackStackImmediate()) {
            return true;
        }
        return super.onSupportNavigateUp();
    }
This method sets the fragment given by its base key,
and optionally starts scrolling to a preference identified by its key
main/src/main/java/cgeo/geocaching/settings/SettingsActivity.java