Layouting problems with JavaFX Region - layout

Question

I want to write a new class that extends Region containing a StackPane inside. But I'm getting into trouble when I add insets to it like padding or a border. Here is a simplified example of the class:
public class CustomPane extends Region
{
private ToggleButton testControl = new ToggleButton("just a test control");
private StackPane rootPane = new StackPane(testControl);
public CustomPane()
{
getChildren().add(rootPane);
setStyle("-fx-border-color: #257165; -fx-border-width: 10;");
}
}
And that is how the result looks like:
If I try to move the StackPane by calling
rootPane.setLayoutX(10);
rootPane.setLayoutY(10);
then the Region just grows:
But really I wanted it to look like this:
(The third image was created by extending StackPane instead of Region, which already manages the layouting stuff correctly. Unfortunately I have to extend Region since I want to keep getChildren() protected.)
Okay, I tried to handle the layout calculation but I didn't come up with it. Could experts give me some advise?

Answer 1

StackPane uses the insets for layouting the (managed) children. Region doesn't do this by default. Therefore you need to override the layoutChildren with something that uses these insets, e.g.:
#Override
protected void layoutChildren() {
Insets insets = getInsets();
double top = insets.getTop(),
left = insets.getLeft(),
width = getWidth() - left - insets.getRight(),
height = getHeight() - top - insets.getBottom();
// layout all managed children (there's only rootPane in this case)
layoutInArea(rootPane,
left, top, // offset of layout area
width, height, // available size for content
0,
HPos.LEFT,
VPos.TOP);
}