title: Callback in parent page from popup form submit in Wicket
body: <p>I have a Wicket page with multiple panels that allows the user to open a new Wicket page in a popup window. The user can enter some data, click submit in the popup and it closes after the submit has been processed.</p>
  
  <p>How do I get a callback in the parent page that the popup has been closed so that I can refresh the parent page (the parent page needs to reflect the data the user entered in the popup)?</p>
  
  <p>Is it possible to receive the callback in the panel of the parent page that was responsible for the popup opening so that I can only refresh the panel itself instead of the full page (this would require to also get the AjaxRequestTarget)?</p>