It's even apparent how to reuse the old stage (i.e...

# tornadofx

[hastebrot]

It's even apparent how to reuse the old stage (i.e. change the stage's scene, without having to care about showing/hiding the stage):

fun main(args: Array<String>) {
    val stage = setupStage { stage ->
        stage.title = "hello javafx"
        stage.scene = Scene(StackPane(Label("hello javafx")), 200.0, 200.0)
        stage.show()
    }
    
    setupStage({ stage }) {
        stage.scene = Scene(StackPane(Label("hello stage")), 200.0, 200.0)
    }
}