title: Validation on onCellChange with Slickgrid
body: <p>I have just started to use slickgrid (++ to the author btw) - running into a few small issues - I want to dynamically update some fields using the in-context editing.  Once editing is done I wish to send this to the server which also should validate what was sent.  If there is an error I would like to handle the error in a similar way to how the validatr event works? e.g. highlight the cell and not let the user to move away until it is valid, however I do not see how I can do so? any advice on this would be much appreciated!</p>
  
  <p>Code so far... </p>
  
  <pre><code>grid.onCellChange.subscribe(function(e, args) {
      var item = args.item;
      var column = args.cell;       
      var row = args.row;
      var value = data[args.row][grid.getColumns()[args.cell].field];
      var id = args.item.id;
      var field = grid.getColumns()[args.cell].field;
      var dataString = "id="+id+"&amp;field="+field+"&amp;value="+value;
      var status = false;
      $.ajax({
          type: "POST",
          url: "/en/&lt;?php echo $this-&gt;controller; ?&gt;/updateattribute/&amp;callback=?'",
          data: dataString,
          dataType: "json",
          success: function(a) {  
              console.log(data);              
              if(a.status == true) {                  
                  status = true;
              } else {
                  status = false;             
              }       
              return false; 
          }
      });    
      if(!status) {
          return false;
      }             
      grid.invalidateRow(data.length);
      data.push(item);
      grid.updateRowCount();
      grid.render();
  });
  </code></pre>
  
  <p>Many thanks</p>