public ObjectProperty<Color> chartGridColorProperty() {
        if (null == chartGridColor) {
            chartGridColor = new ObjectPropertyBase<Color>(_chartGridColor) {
                @Override protected void invalidated() { fireTileEvent(REDRAW_EVENT); }
                @Override public Object getBean() { return Tile.this; }
                @Override public String getName() { return "chartGridColor"; }
            };
            _chartGridColor = null;
        }
        return chartGridColor;
    }
Defines the color that will be used to colorize lines in
charts e.g. the grid in the RadarChartTileSkin
@param COLOR
src/main/java/eu/hansolo/tilesfx/Tile.java