@Override
    public float getCurrentBearing() {
        return AngleUtils.normalize(360 - mMap.getMapPosition().bearing); // VTM uses opposite way of calculating bearing compared to GM
    }
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