code: function setupContainerApi_(containNode_) {
    containNode_.popDesigner = popDesigner_;
    containNode_.saveDesigner = saveDesigner_;
    containNode_.dumpTree = dumpReactTree_;
    containNode_.loadTree = loadReactTree_;
    containNode_.streamTree = streamReactTree_;
    containNode_.listScenePage = listScenePage_;
  
    containNode_.keyOfNode = function (node) {
      return keyOfNode_(node);
    };
    containNode_.splitterMouseDn = function () {
      return splitterMouseDn_;
    };
  }
docs: define APIs for containNode_, for GUI design --------------------------------------------