HTMLEditor formatting lost when selecting all (CTRL-A)

In the HTMLEditor, when selecting all text with a keyboard shortcut (CTRL-A) and focusing another window, then getting back to the HTMLEditor.

Steps to reproduce :
- Run this sample :
"

import javafx.application.Application;
import static javafx.application.Application.launch;
import javafx.scene.Scene;
import javafx.scene.web.HTMLEditor;
import javafx.stage.Stage;

public class TestApp extends Application {

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

    @Override
    public void start(Stage primaryStage) throws Exception {
        HTMLEditor editor = new HTMLEditor();
        
        Scene scene = new Scene(editor);
        primaryStage.setScene(scene);
        primaryStage.show();
    }
}
"
For JDK 8u202 :
1) Write "Hello world"
2) Select the sentence "Hello world" and apply the size 18
3) Hit enter a few time to let some space
4) Write "Test", select it and apply the size 10
5) Do CTRL-A to select all the text
6) Click outside of the JavaFX application, to focus your browser for example.
7) Then select the JavaFX application on the windows taskbar for example

For JDK 11 and OpenJFX 13:
At step 5, the actual behavior is directly observed, no need to loose the focus. One could say

Actual behavior:
- The whole selection has the font-size 18 applied.

Expected behavior:

- Nothing should change