title: Why were window.scrollY and window.scrollX introduced?
body: <p>As far as I know, <code>pageXOffset/pageYOffset</code> properties were already available since Netscape 4 era.<br>
  And it seems <code>scrollX/scrollY</code> were introduced circa Netscape 6.</p>
  
  <p>Alternative question: </p>
  
  <blockquote>
    <p>Q2. Is there a browser which implements scrollX/scrollY but doesn't support pageXOffset/pageYOffset?</p>
  </blockquote>
  
  <p>I will add a third question because no one was able to answer the previous ones:</p>
  
  <blockquote>
    <p>Q3. scrollX/scrollY was added to the latest editor's draft of the CCSOM and the working draft only got pageXOffset/pageYOffset, why are they keeping both attributes?</p>
  </blockquote>