public void setThresholdColor(final Color COLOR) {
        if (null == thresholdColor) {
            _thresholdColor = COLOR;
            fireTileEvent(REDRAW_EVENT);
        } else {
            if (!thresholdColor.isBound()) {
                thresholdColor.set(COLOR);
            }
        }
    }
Defines the color that will be used to colorize the threshold
indicator of the tile.

@param COLOR
src/main/java/eu/hansolo/tilesfx/Tile.java