title: Show or Hide SlickGrid "header" (filter) row at runtime
body: <p>I'm trying to control the visibility of the HeaderRow at runtime.  </p>
  
  <p>[Note:  To clear any confusion: I'm not talking about the row with the column names;  I'm talking about the row that's made visible with grid option "showHeaderRow:true";  i.e., what might be better termed the "Filter Row"].</p>
  
  <p>I'm trying to use:</p>
  
  <pre><code>grid.setOptions({ showHeaderRow: true/false }); 
  grid.invalidate();
  </code></pre>
  
  <p>This seems to have no effect on the grid or the display of the HeaderRow.</p>
  
  <p>Any thoughts on what I'm missing?</p>