Second (and subsequent) calls to setBorder on a subclass of Region does not fully update the Border property. My test is using a single BorderStroke. It seems that the Paint, Widths, Radii, etc get updated but not the Insets.

This program demonstrates the issue:

package sample;

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.layout.*;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class Main extends Application
{
    class SubRegion extends Region
    {
        private final Rectangle rect = new Rectangle(10,10, Color.BLACK);

        SubRegion() {
            getChildren().add(rect);
        }

        @Override
        protected void layoutChildren() {
            Insets in = getInsets();

            System.out.println(in);

            rect.setX(in.getLeft());
            rect.setY(in.getTop());
            rect.setWidth(getWidth() - in.getLeft() - in.getRight());
            rect.setHeight(getHeight() - in.getTop() - in.getBottom());
        }
    }


    @Override
    public void start(Stage stage) throws Exception
    {
        final BorderWidths borderWidth2 = new BorderWidths(2);

        final Insets firstInsets = new Insets(5, 5, 100, 100); // TRBL
        final Insets secondInsets = new Insets(120, 120, 3, 3); // TRBL

        final Border orange_border = new Border(new BorderStroke(Color.ORANGE, BorderStrokeStyle.SOLID, CornerRadii.EMPTY, borderWidth2, firstInsets));
        final Border green_border = new Border(new BorderStroke(Color.GREEN, BorderStrokeStyle.SOLID, CornerRadii.EMPTY, borderWidth2, secondInsets));

        SubRegion sr = new SubRegion();

        //
        // Uncomment lines for these tests:
        //
        // Test Name | Lines UNcommented | Result
        // -----------------|-------------------|-----------------------------------------------
        // orange only | 1 | orange border around black box in upper right
        // green only | 3 | green border around black box in lower left
        // demonstrate bug | 1 and 3 | green border in lower left, black box in the upper right (at the former Insets)
        // workaround | 1, 2 and 3 | same as "green only" ie. correct
        //
        sr.setBorder(orange_border); // line "1"
        //sr.setBorder(null); // line "2"
        sr.setBorder(green_border); // line "3"

        stage.setTitle("Hello World");
        stage.setScene(new Scene(sr, 300, 275));
        stage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}