title: Move div with arrow key in jQuery 1.6.1 does not work
body: <p>In JQuery 1.6.1, we can supposedly use <code>+=</code> or <code>-=</code> with <code>css()</code> just as we can do with <code>animate()</code>, but this isn't working. Does anyone see a problem with the code?</p>
  
  <pre><code>$(document).keydown(function(e) {  
      if (e.which == 37) { //37 left arrow key.
          $('div').css('left', '-=10px')
      }
  });
  </code></pre>
  
  <p>Check <a href="http://jsfiddle.net/QLFEy/3" rel="nofollow">http://jsfiddle.net/QLFEy/3</a></p>