```class MainView: View() { override val root ...

# tornadofx

[claudiug]

class MainView: View() {
    override val root = Pane()
    
    init {
        with(root) {
            prefHeight(800.0)
            prefHeight(600.0)
            if (true) {
                replaceWith(LoginController::class)
            } else {
                replaceWith(RegisterController::class)
            }
        }
    }
}