title: jqGrid show an 'edit' icon for in line editing
body: <p>I am using the jqGrid with inline editing option. I want to show an edit icon if the cell does not have any values.</p>
  
  <p>So I write a formatter:</p>
  
  <pre><code> function aFormatter(cellvalue, options, row) {
          if(cellvalue == null){          
                return 'you can edit this';
          }else{
              return cellvalue;
          }
   }
  </code></pre>
  
  <p>The <code>you can edit this</code> text is displayed, when I click on it an input box is displayed correctly, however the input box as the initial value <code>you can edit this</code> ? </p>
  
  <p>How can I fix it?</p>
  
  <hr>
  
  <p>I am using the jqGrid through <code>struts 2 jquery tags plugin</code>, which is build on jqGrid version </p>