title: Issue with dynamically added tooltip to the grid cells with auto width
body: <p>I add dynamically a tooltip to each cell in a grid in this way:</p>
  
  <pre><code>renderer : function(value, metadata, record)
  {
      metadata.attr = 'ext:qtip="' + value + '" ext:qwidth="auto"';
      return value;
  }
  </code></pre>
  
  <p>It works fine for small text. But when the text is long, that the tooltip have to be larger than 500px, then that tooltip looks really bad. I know that maximum supported width by Sencha is 500px, but I found a solution here: <a href="http://forums.ext.net/showthread.php?15634-Overcoming-ExtJs-Tooltip-s-max-width-of-500" rel="nofollow">http://forums.ext.net/showthread.php?15634-Overcoming-ExtJs-Tooltip-s-max-width-of-500</a>. Unfortunately I don't know how to set that baseCls to my qtips in metadata.attr. I was traying with:</p>
  
  <pre><code>Ext.Tip.prototype.baseCls = 'custom-x-tip';
  </code></pre>
  
  <p>But it doesn't change anything. Of course, I have that css class defined in my css file.</p>