protected void checkExtendedSettingsVisibility(final boolean forceShowAll) {
        lazyInitPreferenceKeys();
        final PreferenceScreen prefScreen = getPreferenceScreen();
        if (prefScreen != null) {
            checkExtendedSettingsVisibilityHelper(prefScreen, forceShowAll);
        }
    }
searches recursively in all elements of given prefGroup for first occurrence of s
returns found preference on success, null else
(prefers preference entries over preference groups)
main/src/main/java/cgeo/geocaching/settings/fragments/BasePreferenceFragment.java