title: jquery blockUI tell if page or specific element is blocked
body: <p>Is there a way to tell if $.blockUI(); has been called but $.unblockUI() has not been called?  Ideally this should be able to work for both blocking the full page and specific elements.</p>
  
  <p>I'd expect it to work something like this</p>
  
  <pre><code>&gt; $.blockUI();
  &gt; $.isBlockUI?():
  &gt;&gt; true
  &gt; $.unblockUI();
  &gt; $.isBlockUI?();
  &gt;&gt; false
  </code></pre>