title: how do I create a textfield which supports numbers only in vaadin
body: <p>I am using a Vaadin text field and I want to restrict it to support numbers only in it. I tried to override <code>setValue()</code> and return without calling super. <code>setValue()</code>  if text is not a number. But it doesn't seems to be working. How can I correct this?
  I am using Vaadin 7. And I think it doesn't support NumberField as well.</p>