title: ExtJS - dirty check on form works only the first time
body: <p>I am doing a dirty check before submitting a Edit details form. This works the first time after the form is loaded, but if I submit the form once, the dirty check ceases to work on subsequent calls. </p>
  
  <pre><code>if(editForm.getForm().isDirty()) {
      editForm.getForm().submit( {
          url:'app/update',
          waitMsg:'Saving data',
          success:function(form,action) {
                Ext.Msg.alert("Success", "Successfully updated");
          },
          failure: function(form,action) {
                Ext.Msg.alert("Failure", "Failed to update");
          }
      });
  } else {
      Ext.Msg.alert("Message", "Nothing has been changed since you last saved.");
  }
  </code></pre>