title: Facebook authentication without login button
body: <p>I have followed some Facebook API 3.0 tutorials, including the Login/Logout and the Publish To Feed examples. So the login works this way:</p>
  
  <ol>
  <li>App opens, shows a fragment which displays a login button</li>
  <li>User clicks login, the authentication is done via the referenced FacebookSDK library (com.facebook.widget.LoginActivity) and the provided code using sessions.</li>
  <li>User is redirected to next screen</li>
  </ol>
  
  <p>I don't want to make the user to login this way. I want them to use my app without any login/registration, then if they click on a facebook specific feature e.g. share a note on Facebook, then the app should ask them whether they let Facebook use their app or something, you know the usual stuff. Without this I get a nullpointer in the publishFeedDialog() function as session is null, because no login has been made.</p>
  
  <p>So my question is, how can I ignore the SplashFragment with the Login button, so when the user clicks on a Facebook feature in my app, no new screen is displayed with a login button, but only the default Facebook authentication window that users are used to?</p>