Does the page visibility API actually support OS screen lock?

Question

According to W3 Page Visibility specification and Mozilla's Page Visibility API documentation, the Page Visibility API supports detecting if a browser window is hidden because of the OS lock screen. Unfortunately, all of the examples I have found seem to indicate that this is not supported. I cannot get any example JS code or any of my JS code to report that the browser was hidden when I lock my screen (on Windows or OS X).
Some of the examples I have tried:

• http://ie.microsoft.com/testdrive/Performance/PageVisibility/Default.html
• https://jsfiddle.net/wvupJ/
• https://jsfiddle.net/fakj0puw/1/

None of these report that the page was hidden when I lock my OS. Is this just not supported even though the documentation indicates otherwise?

Because I have to insert some code to be able to link to JSFiddle...

var results = document.getElementById('results');

function handleVisibilityChange() {
  if (document.webkitHidden) {
    results.innerHTML = results.innerHTML + 'Hidden.<br>';
  } else {
    results.innerHTML = results.innerHTML + 'Visible.<br>';
  }
}

document.addEventListener("webkitvisibilitychange", handleVisibilityChange, false);

Answer 1

It works on OSX with Safari 8. (For lock and screen saver)

However no browser I found works for Windows.

As of 27/04/2015