@Override
    public void selectThemeOptions(final Activity activity) {
        themeHelper.selectMapThemeOptions(activity, currentTileProvider);
        doReapplyTheme = true;
    }
call this instead of VTM.layers().add so that we can keep track of layers added by the tile provider
main/src/main/java/cgeo/geocaching/unifiedmap/mapsforgevtm/MapsforgeVtmFragment.java