title: MVC4's DotNetOpenAuth TwitterClient sample does not respect prior login
body: <p>If I create an ASP.NET MVC 4 Web Application using the <code>Internet Application</code> template, it pre-installs all the components and configuration necessary to implement authentication using a range of OAuth and OpenID providers. Just adding my Twitter consumer key and secret to <code>AuthConfig.cs</code> activates authentication via Twitter.</p>
  
  <p>However, it doesn't seem to work as I would expect.</p>
  
  <p>If I attempt to authenticate using Twitter, it invariably displays a Twitter sign-on page, regardless of whether I am already signed on to Twitter. It also logs me out of Twitter, so that I am forced to re-authenticate on my next browser visit to Twitter.</p>
  
  <p>Is this a bug, or is some additional configuration necessary to transform this into the more usual seamless workflow (which is working correctly for other providers like Google)?</p>
  
  <p>Thanks, in advance.</p>
  
  <p>Tim</p>