public DoubleProperty middleValueProperty() {
        if (null == middleValue) {
            middleValue = new DoublePropertyBase(_middleValue) {
                @Override protected void invalidated() { fireTileEvent(REDRAW_EVENT); }
                @Override public Object getBean() { return Tile.this; }
                @Override public String getName() { return "middleValue"; }
            };
        }
        return middleValue;
    }
Returns the lower right region.
Only if the getSkin() != null
@return the lower right region
src/main/java/eu/hansolo/tilesfx/Tile.java