form.add(new CheckBox("showStateless", new PropertyModel<Boolean>(this,
"showStatefulAndParentsOnly")));
form.add(new CheckBox("showBehaviors", new PropertyModel<Boolean>(this, "showBehaviors")));
form.add(new CheckBoxMultipleChoice<>("visibleColumns",
new PropertyModel<List<IColumn<TreeNode, Void>>>(this, "visibleColumns"), allColumns).setSuffix(" "));
form.add(new AjaxFallbackButton("submit", form)
{
private static final long serialVersionUID = 1L;
@Override
protected void onAfterSubmit(AjaxRequestTarget target, Form<?> form)