     }
 
     /// show value labels next to thumbs. (default: show no label)
-    @IBInspectable public var valueLabelPosition: NSLayoutAttribute = .notAnAttribute {
+    @IBInspectable open var valueLabelPosition: NSLayoutAttribute = .notAnAttribute {
         didSet {
             valueLabels.removeViewsStartingAt(0)
             if valueLabelPosition != .notAnAttribute {


    // MARK: - Appearance

    @IBInspectable public var thumbImage: UIImage? {
        didSet {
            thumbViews.forEach {$0.image = thumbImage}
            let halfHeight = (thumbImage?.size.height ?? 2)/2 - 1 // 1 pixel for semi-transparent boundary
            trackView.layoutMargins = UIEdgeInsets(top: halfHeight, left: 0, bottom: halfHeight, right: 0)
        }
    }
    @IBInspectable public var minimumImage: UIImage? {
        get {
            return minimumView.image
        }

        setup()
    }

    override open func prepareForInterfaceBuilder() {
        // make visual editing easier
        layer.borderWidth = 0.5
        layer.borderColor = UIColor.lightGray.withAlphaComponent(0.5).cgColor
