private class MyDialog: Fragment() {

    override val root = VBox()
    private var ok: Button by singleAssign()
    private var cancel: Button by singleAssign()
    var value: Observable<Boolean> by singleAssign()
	
    init {
        title = "My Dialog"

        with(root) {
            hbox {
                ok = button("OK")
                cancel = button("CANCEL")
            }
            value = Observable.merge(
                    ok.actionEvents().map { true }.doOnNext { closeModal() },
                    cancel.actionEvents().map { false }.doOnNext { closeModal() }
            ).take(1)
        }
    }
}