title: Undocumented behaviour in jQuery?
body: <p>Is the following behaviour documented (i.e. should I rely on it)?</p>
  
  <p>Due to an error, I had a dialog box and referred to its id using a bare word in javascript. Surprisingly, I did not get an error and the code worked as intended,</p>
  
  <p>The example (on JSFiddle.net <a href="http://jsfiddle.net/N4Axw/" rel="nofollow">here</a>) has a 2 simple dialog boxes</p>
  
  <pre><code>&lt;div id="Hello"&gt;
     &lt;input id="box1" name="box1" type="text" value="not change"&gt;
  &lt;/div&gt;
  &lt;div id="Goodbye"&gt;
     &lt;input id="box1" name="box1" type="text" value="not change"&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>And javascript which is missing the line <code>Hello = $("#Hello");</code>.</p>
  
  <pre><code>$("#Hello").dialog({
      autoOpen:false, 
      modal:true, 
      width:"auto"}
  );
  $("#Hello").dialog("open");
  $("#Goodbye").dialog("open");
  $('[name="box1"]',Hello).val("test");  
  </code></pre>
  
  <p>Surprisingly, the last line updates the textbox in the <code>Hello</code> div, but I can't find anywhere where this behaviour is documented. Is it just an obscure side effect, not to be relied on, or is this a valid jQuery selector style?</p>
  
  <p>FYI, I'm using Chrome Version 32.0.1700.107 m.</p>