private void updateRoutingPrefs(final boolean useInternalRouting) {
        final boolean anyRoutingAvailable = useInternalRouting || ProcessUtils.isInstalled(getString(R.string.package_brouter));
        PreferenceUtils.setEnabled(findPreference(getString(R.string.pref_brouterDistanceThreshold)), anyRoutingAvailable);
        PreferenceUtils.setEnabled(findPreference(getString(R.string.pref_brouterShowBothDistances)), anyRoutingAvailable);
    }
Fill the choice list for default navigation tools.
main/src/main/java/cgeo/geocaching/settings/fragments/PreferenceNavigationFragment.java