title: FirebaseUI for Web — Auth - how to re-authenticate?
body: <p>I'm using FirebaseUI for Web — Auth widget to simplify the auth workflow, and I'm stuck with a problem. Everything works OK the first time. But, after I sign in, the widget contents clears away, and the 'Sign in with ...' buttons never come back. Trying to recreate the widget brings up the error "UI Widget is already initialized on the page. Only one widget instance can be initialized per page."</p>
  
  <p>This means that users need to refresh the page to get the sign-in buttons back. Is there a more elegant way?</p>