How to add css class on validation error to list item <p>In my application I have ListView with textField which is validating when user submit button. When there is error it will show error message. Problem is there is a lot of rows so user can not recognize bad row easily. So is there some way how to add css class to this bad row after submitting button ?</p> <pre><code> private void addListView() { add(new PropertyListView&lt;MyClass&gt;("view") { private static final long serialVersionUID = 1L; @Override protected void populateItem(final ListItem&lt;MyClass&gt; listItem) { listItem.add(new TextField&lt;String&gt;("result") { private static final long serialVersionUID = 1L; @SuppressWarnings("unchecked") @Override public final &lt;String&gt; IConverter&lt;MyClass&gt; getConverter(Class&lt;MyClass&gt; type) { return (IConverter&lt;MyClass&gt;) StringConverter.getInstance(); } }); }); } </code></pre>