public HtmlNode InsertAfter(HtmlNode newChild, HtmlNode refChild) { if (newChild == null) { throw new ArgumentNullException("newChild"); } if (refChild == null) { return(PrependChild(newChild)); } if (newChild != refChild) { int num = -1; if (_childnodes != null) { num = _childnodes[refChild]; } if (num == -1) { throw new ArgumentException(HtmlDocument.HtmlExceptionRefNotChild); } if (_childnodes != null) { _childnodes.Insert(num + 1, newChild); } _ownerdocument.SetIdForNode(newChild, newChild.GetId()); _outerchanged = true; _innerchanged = true; } return(newChild); }