title: How to change cell formatting dynamically
body: <p>I hava implemented a datagrid using dojo which get updated every 5 seconds. I use following code to update the datagrid.</p>
  
  <pre><code>jsonStore.fetch({
           query: {id:'*'},
           onComplete: function(items, result){
           dojo.forEach(items, function(item){
               jsonStore.setValue(item, "time" , data.update[0].netchange);
  .....
  </code></pre>
  
  <p>'data' is the new data i need to set to the grid which is an json object as follows</p>
  
  <pre><code>var data = {"update":[{...}]}
  </code></pre>
  
  <p>what I need to do if the netchage is negative i need set cell color to red. if netchange is positive it should be green. So I need a way to change cell formatting dynamically. can some one please tell me how to this. thanks in advance</p>
  
  <pre><code>grid4 = new dojox.grid.DataGrid({
              query : {
                  Title : '*'
              },
              id : "grid",
              jsId : "grid",
              clientSort : true,
              rowSelector : '0px',
              structure : layout4
          }, document.createElement('div'));
          grid4.setStore(jsonStore);
          dojo.byId("gridContainer4").appendChild(grid4.domNode);
  
  var layout4 = [ {
              field : 'time',
              name : 'time',
              width : '40px',
              formatter: geticon()
          }, {
              field : 'netchange',
              name : 'netchange',
              width : '30px'
          } ];
  </code></pre>