Code

  _diagram.SerializeTag += new SerializeTagEventHandler(this.SerializeTag);
  _diagram.SaveToXml(fileName);

  private void SerializeTag(object sender, MindFusion.Diagramming.SerializeTagEventArgs e)
	  {
		object tag = null;
		string xmlTag = "";
		string stringRepresentation = "";

		e.Handled = true;

		if (e.Object is DiagramItem)
		{
		    tag = (e.Object as DiagramItem).Tag;
		    if (tag is VectorNodeProps)
			  xmlTag =Util.ObjectXMLSerializer(.....

		    if (tag is string)
		    {
			  xmlTag = (string)tag;
		    }

		}
		if (e.Object is Diagram)
		{
		    tag = (e.Object as Diagram).Tag;
		    xmlTag = Util.ObjectXMLSerializer(....
		}

		if (tag != null)
		{
		    stringRepresentation = tag.GetType().ToString();
		    stringRepresentation += ";";
		    stringRepresentation += xmlTag;
		}

		XmlNode repNode = e.Context.XmlDocument.CreateTextNode(stringRepresentation);
		e.Representation.AppendChild(repNode);
	  }
 

Code

 _diagram.DeserializeTag += new SerializeTagEventHandler(this.DeserializeTag);
 _diagram.LoadFromXml(fileName);


 private void DeserializeTag(object sender, MindFusion.Diagramming.SerializeTagEventArgs e)
	  {
 XmlText textNode = e.Representation.LastChild as XmlText;
		string stringRep = textNode.Value;
		int pos = stringRep.IndexOf(";");

		if (pos == -1)
		    return;

		string type = stringRep.Substring(0, pos);
		string xml = stringRep.Substring(pos + 1);
		object tag = null;
		Type t = Type.GetType(type);

 if (t == typeof(MyClass))
		{
		  tag = Util.ObjectXMLSerializer(......)
		   .....
		   .....
		}
   if (t == typeof(string))
		{
		    tag = xml;
		}

		if (e.Object is Group)
		    ((Group)e.Object).Tag = tag;
		else if (e.Object is DiagramItem)
		    ((DiagramItem)e.Object).Tag = tag;
		else if (e.Object is Diagram)
		    ((Diagram)e.Object).Tag = tag;
	  }
 

Code

System.FormatException was caught
  Message="Input string was not in a correct format."
  Source="MindFusion.Diagramming"
  StackTrace:
	 at MindFusion.Diagramming.Diagram.LoadFromXml(XmlDocument document)
	 at MindFusion.Diagramming.Diagram.LoadFromXml(String fileName)
	 at Gui.ViewFormControls.DataFlowControl.LoadDataFlow(String fileName, Diagram _flowChart) in ....