var items = [{
    id: -1,
  pId: -2,
  value: "根目录",
  text: "根目录"
}, {
    id: 1,
  pId: -1,
  value: "第一级目录1",
  text: "第一级目录1"
}, {
    id: 11,
  pId: 1,
  value: "第二级文件1",
  text: "第二级文件1"
}];

BI.createWidget({
  type: "bi.multi_tree_combo",
  itemsCreator: function (options, callback) {
        callback({
          items: items
        });
  },
  width: 300
})