 //MARK: KSButton
 extension KSTabView {
     class KSButton: NSControl {
+
         var trackingArea: NSTrackingArea!
         private let parentTabView: KSTabView
         private var mouseInside = false {

        }
    }
}

private class KSButtonCell: NSButtonCell {
    override func drawTitle(title: NSAttributedString, withFrame frame: NSRect, inView controlView: NSView) -> NSRect {
        return super.drawTitle(self.attributedTitle, withFrame: frame, inView: controlView)
    }
}

private class UnderLine: NSBox {
    init() {
        super.init(frame: NSZeroRect)
        self.boxType = NSBoxType.Custom
        self.borderWidth = 0
        self.fillColor = NSColor.whiteColor()
        self.hidden = true
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}


            self.identifier = identifier
        
            batton.setCell(ButtonCell())
            batton.title = title
            batton.image = imagea
            batton.image?.size = NSMakeSize(parentTabView.fontSize * 1.5, parentTabView.fontSize * 1.5)
