8290990: Clear .root style class from a root node that is removed from a Scene/SubScene

Reviewed-by: jhendrikx, aghaisas, mhanl

Author: Michael Strauß

modules/javafx.graphics/src/main/java/javafx/scene/Scene.java

@@ -1223,6 +1223,7 @@ protected void invalidated() {
 
                     if (oldRoot != null) {
                         oldRoot.setScenes(null, null);
+                        oldRoot.getStyleClass().remove("root");
                     }
                     oldRoot = _value;
                     _value.getStyleClass().add(0, "root");

modules/javafx.graphics/src/main/java/javafx/scene/SubScene.java

@@ -316,6 +316,7 @@ protected void invalidated() {
                     if (oldRoot != null) {
                         StyleManager.getInstance().forget(SubScene.this);
                         oldRoot.setScenes(null, null);
+                        oldRoot.getStyleClass().remove("root");
                     }
                     oldRoot = _value;
                     _value.getStyleClass().add(0, "root");

modules/javafx.graphics/src/test/java/test/javafx/scene/SceneTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -222,6 +222,17 @@ public void testRootUpdatedWhenChangedInScene() {
         assertEquals(scene, g2.getScene());
     }
 
+    @Test
+    public void testRootStyleClassIsClearedWhenRootNodeIsRemovedFromScene() {
+        Scene scene = new Scene(new Group());
+        Group g = new Group();
+        assertFalse(g.getStyleClass().contains("root"));
+        scene.setRoot(g);
+        assertTrue(g.getStyleClass().contains("root"));
+        scene.setRoot(new Group());
+        assertFalse(g.getStyleClass().contains("root"));
+    }
+
     @Test
     public void testNodeUpdatedWhenAddedToScene() {
         Group root = new Group();

modules/javafx.graphics/src/test/java/test/javafx/scene/SubSceneTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -41,6 +41,7 @@
 import javafx.scene.SubSceneShim;
 import javafx.scene.layout.Pane;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNull;
 import org.junit.Test;
 import static org.junit.Assert.assertTrue;
@@ -131,6 +132,17 @@ public void testRootUpdatedWhenChangedInSubScene() {
         assertEquals(subScene, NodeShim.getSubScene(g2));
     }
 
+    @Test
+    public void testRootStyleClassIsClearedWhenRootNodeIsRemovedFromSubScene() {
+        SubScene scene = new SubScene(new Group(), 10, 10);
+        Group g = new Group();
+        assertFalse(g.getStyleClass().contains("root"));
+        scene.setRoot(g);
+        assertTrue(g.getStyleClass().contains("root"));
+        scene.setRoot(new Group());
+        assertFalse(g.getStyleClass().contains("root"));
+    }
+
     @Test
     public void testSetCamera() {
         Camera camera = new PerspectiveCamera();