title: Checking if browser is in fullscreen
body: <p>Is there a way to check if a browser is currently in fullscreen mode (after the user pressed f11)?</p>
  <p>Something like:</p>
  <pre><code>if (window.fullscreen) {
    // it's fullscreen!
  }
  else {
    // not fs!
  }
  </code></pre>
  <p>Thanks.</p>
  <p>Steerpike's answer is pretty good, but my comment:</p>
  <blockquote>
  <p>Thanks a lot, but this answer is not
  sufficient for FF. In Chrome I can set
  a small tolerance, but in FF the
  urlbar and tabs takes a while to
  disappear, which means after pressing
  f11, the detected window.innerWidth is
  still too small.</p>
  </blockquote>