Slider + disabling actions

Slider.swift

@objc private func valueChanged(_ sender: Slider) {
        // Step 9
        CATransaction.begin()
        CATransaction.setDisableActions(true)
        let thumbRectA = thumbRect(forBounds: bounds, 
                                   trackRect: trackRect(forBounds: bounds), 
                                   value: value)
        trackLayer.frame = .init(x: 0, 
                                 y: frame.height / 4, 
                                 width: thumbRectA.midX, 
                                 height: frame.height / 2)
        // Step 9
        CATransaction.commit()
}