Code reacting to a UI Slider updating line width to outline text.

updatePreviewFromThicknessChange.swift

fileprivate func updatePreviewFromThicknessChange() {
    if thicknessAdjuster.value != lineWidth {
        thicknessSwatch.setNeedsDisplay()  // refresh assuming value adjusted
        lineWidth = thicknessAdjuster.value
        textStyle.drawStyle = textStyle.drawStyle.butWith(
          lineWidthTenths: Int(lineWidth*10))
        updateFontStyling()
        updateFontDisplay()
    }
}