A Java Swing window with a blinking title bar

BlinkingTitleBarDemo.kt

package com.thomaskuenneth

import kotlinx.coroutines.*
import java.awt.*
import java.awt.event.*
import javax.swing.*
import javax.swing.UIManager.*
import javax.swing.plaf.*
import java.lang.System.*

fun main() {
    GlobalScope.launch(Dispatchers.Main) {
        // configure UIManager
        setLookAndFeel(getCrossPlatformLookAndFeelClassName())
        JFrame.setDefaultLookAndFeelDecorated(true)
        // create and setup JFrame
        JFrame("BlinkingTitleBarDemo").apply {
            var lastTimer = 0L
            addComponentListener(object : ComponentAdapter() {
                override fun componentResized(e: ComponentEvent?) {
                    lastTimer = currentTimeMillis()
                }

                override fun componentMoved(e: ComponentEvent?) {
                    lastTimer = currentTimeMillis()
                }
            })
            contentPane.add(JLabel("Hello Kotlin!", SwingConstants.CENTER).apply {
                font = font.deriveFont(72f)
            }, BorderLayout.CENTER)
            defaultCloseOperation = JFrame.EXIT_ON_CLOSE
            size = Dimension(600, 200)
            setLocationRelativeTo(null)
            // let it blink
            launch(Dispatchers.Main) {
                var state = false
                while (isActive) {
                    getDefaults()["activeCaption"] =
                            ColorUIResource(if (state) Color.lightGray else Color.blue)
                    getDefaults()["activeCaptionText"] =
                            ColorUIResource(if (state) Color.blue else Color.lightGray)
                    if (currentTimeMillis() - lastTimer >= 1000) {
                        SwingUtilities.updateComponentTreeUI(rootPane)
                    }
                    state = !state
                    delay(1000)
                }
            }
            isVisible = true
        }
    }
}