title: Wicket 6 AjaxFormComponentUpdatingBehavior event working on first row of ListView but not for subsequent ones
body: <p>I'm trying to handle a DropDownChoice onchange event in a listView that can display a modal window. It seems working fine for first element but not for subsequent added elements.</p>
  
  <pre><code>final ModalWindow modal = new ModalWindow("modal");
  modal.setOutputMarkupId(true);
  form.add(modal);
  
  final ListView&lt;CommandeFournisseurDetails&gt; myView = new     ListView&lt;CommandeFournisseurDetails&gt;(
              "rowsList",
              new PropertyModel&lt;List&lt;CommandeFournisseurDetails&gt;&gt;(this,
                      "rows")) {
          @Override
          protected void populateItem(
                  final ListItem&lt;CommandeFournisseurDetails&gt; item) {
  
              final CommandeCollectionJDBC myCollection = new CommandeCollectionJDBC();
              CommandeFournisseurDetails row = item.getModelObject();
  
              item.add(new Label("index",
                      new AbstractReadOnlyModel&lt;Integer&gt;() {
                          @Override
                          public Integer getObject() {
                              return item.getIndex() + 1;
                          }
                      }));
  
                      final DropDownChoice&lt;String&gt; ID_PRODUIT = new DropDownChoice(
                      "ID_PRODUIT", new PropertyModel&lt;String&gt;(row,
                              "ID_PRODUIT"), myCollection.getProduit());
              ID_PRODUIT.setOutputMarkupId(true);
              ID_PRODUIT.setMarkupId("ID_PRODUIT");
              ID_PRODUIT.setLabel(Model.of("Produit"));
              ID_PRODUIT.setRequired(true);
  
              AjaxFormComponentUpdatingBehavior behavior = new AjaxFormComponentUpdatingBehavior(
                      "onChange") {
                  protected void onUpdate(AjaxRequestTarget target) {
                      if (!ID_PRODUIT.getDefaultModelObjectAsString()
                              .isEmpty()) {
                          final PageParameters params = new PageParameters();
                          params.set("message",
                                  ID_PRODUIT.getDefaultModelObjectAsString());
                          params.set("type", "Produit");
  
                          modal.setPageCreator(new ModalWindow.PageCreator() {
                              public Page createPage() {
                                  // Use this constructor to pass a reference
                                  // of this page.
                                  return new ModalContentPage(modal, params);
                              }
                          });
  
                          modal.show(target);
  
                          target.add(modal);
  
                          target.add(ID_PRODUIT);
                      }
  
                  }
  
                  protected void onError(AjaxRequestTarget target,
                          RuntimeException e) {
                      System.out.println(e.toString());
                  }
  
              };
              ID_PRODUIT.add(behavior);
  
                              AbstractSubmitLink remove = new SubmitLink("removeRowLink") {
                  @Override
                  public void onSubmit() {
                      getList().remove(item.getModelObject());
                      getParent().getParent().removeAll();
  
                  };
              }.setDefaultFormProcessing(false);
  
              item.add(remove);
  
          }
      }.setReuseItems(true);
  
      form.add(new SubmitLink("addRowLink") {
          @Override
          public void onSubmit() {
              rows.add(new CommandeFournisseurDetails());
          }
      }.setDefaultFormProcessing(false));
  
      myView.setOutputMarkupId(true);
  
      form.add(myView);
  </code></pre>
  
  <p>Any idea why the other elements do not inherit the same event?
  Thanks for your help.</p>