                 {
                     setNeedsLayout()
                     
-                    if keyPath == "isHidden" && !(change![.newKey] as! Bool)
+                    if keyPath == "hidden" && !(change![.newKey] as! Bool)
                     {
                         sbv.setNeedsDisplay()
                     }

    override open func didAddSubview(_ subview: UIView) {
        super.didAddSubview(subview)
        
        subview.addObserver(self, forKeyPath:"isHidden", options: [.new, .old], context: nil)
        subview.addObserver(self, forKeyPath:"frame", options: [.new, .old], context: nil)
        subview.addObserver(self, forKeyPath:"center", options: [.new, .old], context: nil)


        
        
        
        if (keyPath == "frame" || keyPath == "hidden" || keyPath == "center")
        {
            
            if !self.tg_isLayouting
