code: function saveState(instanceId, stateObject, successCallback, errorCallback) {
          var strObject = JSON.stringify(stateObject);
          return neon.util.ajaxUtils.doPostJSON({
              instanceId: instanceId,
              state: strObject
          }, neon.serviceUrl('widgetservice', 'savestate'), {
              success: successCallback,
              error: errorCallback,
              global: false
          });
      }
docs: Save the current state of a widget.
  @method saveState
  @param {String} instanceId a unique identifier of an instance of a widget
  @param {Object} stateObject an object that is to be saved.
  @param {Function} successCallback The callback to execute when the state is saved. The callback will have no data.
  @param {Function} errorCallback The optional callback when an error occurs. This is a 3 parameter function that contains the xhr, a short error status and the full error message.
  @return {neon.util.AjaxRequest} The xhr request object