Unconfigure a form while the model change can produce random exceptions

[Rizen59]

Unconfigure a form while the model change can produce random exceptions.

It can be explained by multiple reasons :

• the form is still "attached" to model listeners during the unconfiguration process start
• changing the model from any thread can trigger change in view, but some elements are currently unconfigured

Here is a unit test that show to problem :

public class Issue199Test {

    @Rule
    public JavaFXRule javaFXRule = new JavaFXRule();

    @Rule
    public FailOnUncaughtExceptionRule failOnUncaughtExceptionRule = new FailOnUncaughtExceptionRule();

    public class Bean {
        private StringProperty value = new SimpleStringProperty();
        public String getValue() { return value.get(); }
        public StringProperty valueProperty() { return value; }
        public void setValue(String value) { this.value.set(value); }
    }

    @Test
    public void testToUnconfigureFormDuringAModelChange() throws InterruptedException {
        Bean bean = new Bean();
        FXForm form = new FXForm();
        form.setSource(bean);

        Thread thread = new Thread(() -> {
            while (true) {
                bean.setValue(UUID.randomUUID().toString());
            }
        });
        thread.start();
        Thread.sleep(3000); // Wait a little to be sure thread is start

        form.setSource(null);
    }
}