public void setInnerShadowEnabled(final boolean ENABLED) {
        if (null == innerShadowEnabled) {
            _innerShadowEnabled = ENABLED;
            fireTileEvent(REDRAW_EVENT);
        } else {
            if (!innerShadowEnabled.isBound()) {
                innerShadowEnabled.set(ENABLED);
            }
        }
    }
Defines if an inner shadow should be drawn on the tile
background.

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