ScalaFX: Not catching cursor keypresses when button is added

In my scalafx.scene, i catch key events this way:

scene = new Scene(300, 300) {
    val btn_startstop = new Button("Start")
    onKeyPressed = (ev:KeyEvent) => {
        if( ev.code == KeyCode.LEFT ) {
    content = List(btn_startstop)

This works with “normal” keys like the a-z keys, but not with the cursor keys. These seem to be catched away by the button. When I remove the button, cursor key presses are then also catched by the scene.

How can i prevent the button to capture any key presses? It shall react only to mouse clicks.

You may want to also ask about this in a JavaFX community – IIRC, ScalaFX is a fairly thin shell around JavaFX, so this is probably an issue in the underlying library.

You can control who is handling which events using event filters. There is more on that in JavaFX documentation:

A ScalaFX example of doing that is here:

A good way to ask questions about ScalaFX is to post them on StackOverflow using ScalaFX tag:

A JavaFX tag can be added, as needed, to reach that community too.