code: function(interval) {
          this.stopPolling();
          var task = new Ext.util.TaskRunner(interval);
          task.start({
              interval: 0,
              run: this.checkChange,
              scope: this
          });
          this.pollTask = task;
      }
docs: Start an interval task to continuously poll all the fields in the form for changes in their
  values. This is normally started automatically by setting the {@link #pollForChanges} config.
  @param {Number} interval The interval in milliseconds at which the check should run.