FULL PRODUCT VERSION :
java version "1.8.0_131"
Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
ver 1703

A DESCRIPTION OF THE PROBLEM :
When I change the scene graph and the new root contains a HTMLEditor, then a NullPointerException is thrown.

See the source code of the class "HTMLEditorBug".

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
compile and run the class "HTMLEditorBug"

ACTUAL -
NullPointerException

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at com.sun.javafx.scene.web.skin.HTMLEditorSkin.updateToolbarState(HTMLEditorSkin.java:964)
at com.sun.javafx.scene.web.skin.HTMLEditorSkin.lambda$populateToolbars$13(HTMLEditorSkin.java:580)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:361)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.beans.property.ObjectPropertyBase.fireValueChangedEvent(ObjectPropertyBase.java:105)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146)
at javafx.scene.control.ComboBoxBase.setValue(ComboBoxBase.java:150)
at com.sun.javafx.scene.web.skin.HTMLEditorSkin.lambda$populateToolbars$12(HTMLEditorSkin.java:549)
at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
at java.lang.Thread.run(Unknown Source)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
package javaBugs;

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.StackPane;
import javafx.scene.web.HTMLEditor;
import javafx.stage.Stage;

public class HTMLEditorBug extends Application{

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

@Override
public void start(Stage primaryStage) throws Exception {
Label label = new Label("Pane 1");
StackPane pane1 = new StackPane(label);
pane1.setPadding(new Insets(10));

Scene scene = new Scene(pane1, 600, 400);
primaryStage.setScene(scene);
primaryStage.show();

HTMLEditor editor = new HTMLEditor();
StackPane pane2 = new StackPane(editor);
pane2.setPadding(new Insets(10));

scene.setRoot(pane2);
}
}
---------- END SOURCE ----------