popupstandalone.kt

fun main(arguments: Array<String>) {
    Application.launch(App::class.java)
}

class App : Application() {
    override fun start(primaryStage: Stage) {
        primaryStage.title = "Popup Example"
        primaryStage.initStyle(StageStyle.UTILITY)
        primaryStage.opacity = 0.0

        primaryStage.scene = Scene(Region())
        primaryStage.show()

        val popup = Popup()

        popup.x = 600.0
        popup.y = 400.0
        popup.content.addAll(Circle(25.0, 25.0, 50.0, Color.AQUAMARINE))
        popup.show(primaryStage)
    }
}