A DESCRIPTION OF THE PROBLEM :
Since JavaFX 19 the popup of ComboBoxes don't close anymore when the selection changes. This behavior can be tracked down to the introduction of the focusWithin-Property.

REGRESSION : Last worked in version 17

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1) ComboBox with a number of items
2) Last item is initally selected
3) Open ComboBox with mouse or keyboard
4) Select different entry

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Popup of ComboBox closes
ACTUAL -
Popup of ComboBox remains opened

---------- BEGIN SOURCE ----------
public class BugReproduce_L15_61028 extends Application {

    @Override
    public void start(Stage primaryStage) {


     GridPane root = new GridPane();
     root.setHgap(10);
     root.setVgap(10);

        Scene scene = new Scene(root, 600, 400);

        ComboBox<Person> comboBox1 = new ComboBox<>();
        Label label1 = new Label();

        root.add(new Label("Last item selected: "), 0, 0);
        root.add(comboBox1, 1, 0);
        root.add(label1, 2, 0);

        ComboBox<Person> comboBox2 = new ComboBox<>();
        Label label2 = new Label();

        root.add(new Label("Other item selected: "), 0, 1);
        root.add(comboBox2, 1, 1);
        root.add(label2, 2, 1);

        ObservableList<Person> personList = FXCollections.observableArrayList();
        Person person1 = new Person("name1", 12); //$NON-NLS-1$
        Person person2 = new Person("name2", 33); //$NON-NLS-1$
        Person person3 = new Person("name3", 44); //$NON-NLS-1$
        Person person4 = new Person("name4", 44); //$NON-NLS-1$
        Person person5 = new Person("name5", 44); //$NON-NLS-1$
        Person person6 = new Person("name6", 44); //$NON-NLS-1$

        personList.setAll(person1, person2, person3, person4, person5, person6);


        comboBox1.getSelectionModel().selectedItemProperty().addListener((ob, ov, nv) -> label1.setText(nv.getName()));
        comboBox2.getSelectionModel().selectedItemProperty().addListener((ob, ov, nv) -> label2.setText(nv.getName()));

        comboBox1.setValue(person6);
        comboBox1.itemsProperty().set(personList);

        comboBox2.setValue(person1);
        comboBox2.itemsProperty().set(personList);


        primaryStage.setScene(scene);
        primaryStage.show();


    }

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

    public static class Person {
        private StringProperty nameProperty = new SimpleStringProperty();
        private IntegerProperty ageProperty = new SimpleIntegerProperty();

        public Person(String name, Integer age) {
            setName(name);
            setAge(age);
        }

        public StringProperty nameProperty() {
            return nameProperty;
        }

        public void setName(String name) {
            nameProperty.set(name);
        }

        public String getName() {
            return nameProperty.get();
        }

        public IntegerProperty ageProperty() {
            return ageProperty;
        }

        public void setAge(Integer age) {
            ageProperty.set(age);
        }

        public Integer getAge() {
            return ageProperty.get();
        }

        @Override
        public String toString() {
            return "" + getName() + "/" + getAge(); //$NON-NLS-1$ //$NON-NLS-2$
        }
    }
}
---------- END SOURCE ----------

FREQUENCY : always