Still can't tab: tabSpaces = 0 and enableTabKeyTools = true;

Okay. I figured this out. I figured it was (but couldn't narrow it down to yet), my own project's context. I now understand it.
In the source for tab/plugin.js, there is are methods called focusNext and focusPrevious getting added to the editor. It uses this loop to find out what the next element with a tabIndex is, and then focusing on it.

element = this.getNextSourceNode( ignoreChildren, CKEDITOR.NODE_ELEMENT );
while ( element )
{
   if ( element.isVisible() && element.getTabIndex() === 0 )
   {
      elected = element;
      break;
   }
   element = element.getNextSourceNode( false, CKEDITOR.NODE_ELEMENT );
}

Well, here's my relevant html:

<label>Long Description:</label>
       <textarea name="case_study[ldesc]" rows="8" cols="60">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Morbi ornare faucibus urna, non consequat nisl lacinia vitae. Vestibulum ante ipsum primis in faucibus orci luctus.</textarea>
<script type="text/javascript">//<![CDATA[
CKEDITOR.replace('case_study[ldesc]', {"enterMode":CKEDITOR.ENTER_BR,"tabSpaces":0,"0":"id=\"case_study_ldesc\"","on":{"instanceReady":CKeditor_OnComplete,"blur":function(e) { e.editor.updateElement(); }}});
//]]></script>

<fieldset>
       <label>Client:</label>
       <select name="case_study[client_id]" class="txt">
          <option value="">Select...</option>
...

The issue is that (on webkit at least) fieldset nodes get a default tabIndex of 0. So the code tries to focus on a fieldset, but the fieldset node isn't a focusable node.
In source, I just added:

   if ( element.isVisible() && element.getTabIndex() === 0  && element.getName() != 'fieldset')
   {

And I'm adding that to my compiled version manually in a moment.

So there's my solution.

Anyone have thoughts if there's a better way? I don't have always have control over the html, so this seems "mostly scalable" in that regard.