code: function deepFirstFindNav_(widget,groundId) {
    var compObj = widget.component;
    if (!compObj) return null;
    
    for (var sKey in compObj.$gui.compIdx) {
      var child = widget[sKey];
      var childObj = child && child.component;
      if (!childObj) continue;
      
      if (childObj.props['isNavigator.']) {
        var d = childObj.$gui.navItems;
        var ele = d && d[groundId];
        if (ele && ele.props['isPlayground.']) return child;
      }
      else {
        if (!childObj.props['childInline.']) {
          child = deepFirstFindNav_(child,groundId)
          if (child) return child;
        }
      }
    }
    
    return null;
  }
docs: API for reference by path --------------------------