public BooleanProperty flatUIProperty() {
        if (null == flatUI) {
            flatUI = new BooleanPropertyBase(_flatUI) {
                @Override protected void invalidated() { fireTileEvent(REDRAW_EVENT); }
                @Override public Object getBean() { return Tile.this; }
                @Override public String getName() { return "flatUI"; }
            };
        }
        return flatUI;
    }
Defines if the UI should be more flat than skeuomorphic. At the moment only
used in the LedTileSkin
@param FLATUI
src/main/java/eu/hansolo/tilesfx/Tile.java