title: How does the Spotify Windows desktop application authenticate the user?
body: <p>I noticed that the Windows desktop Spotify application asks me for my facebook username and password in the login screen. I am wondering what happens behind the scenes.</p>
  
  <p>When I change my fb password in my browser I have to use the new password in the Spotify desktop app login screen. There are even situations when the Spotify desktop application shows me a fb popup where I have to grant permissions for Spotify itself.</p>
  
  <p>I know that Spotify uses an embedded Chromium browser engine to do all the heavy lifting. But isn't it against Facebooks TOS to do it that way?</p>
  
  <p>I mean, does Spotify posts my username and password to the facebook login.php and intercepts the result page to get my cookie? Is there a documented way to handle a login to facebook on behalf of the user in a proper way?</p>