JavaFX: Align Buttons inside ButtonBar (using SceneBuilder or fxml)

Question

I have a JavaFX ButtonBar with two Buttons (created via SceneBuilder).

I want one of the buttons to be left-aligned and the other right-aligned. (see screenshot)

From the docs I already know how I could achieve this inside the java-source-code:

ButtonBar.setButtonData(newButton, ButtonData.LEFT);

BUT

I want to know how to achieve this WITHOUT having to write this inside my java-files but
how I can achieve this using just SceneBuilder or the corresponding fxml file.

My .fxml file currently looks like this:

<ButtonBar>
  <buttons>
    <Button text="New" />
    <Button text="Save" />
  </buttons>
</ButtonBar>

* I'm on Windows
** This answer is not what I want, because he is using a ToolBar, but I want to know how to do this with a ButtonBar (and his approach does not work for the ButtonBar)

Answer 1

After some Trial and Error I found at least a way to do it directly via the .fxml-file:

You can assign the Button elements with ButtonBar.buttonData attributes and then assign a value to them.

<ButtonBar>
  <buttons>
    <Button text="New" ButtonBar.buttonData="LEFT" />
    <Button text="Save" ButtonBar.buttonData="RIGHT" />
  </buttons>
</ButtonBar>

The docs for the ButtonBar.ButtonData enum are pretty straighforward. So I found the solution to my problem with the "LEFT" and "RIGHT" enum values.

STILL

If anyone knows/finds out how to do this directly in SceneBuilder, I would be grateful!