I am currently evaluating the trial version.

I am getting the same following error when using CopyToClipboard, CutToClipboard, and SaveToFile:

Type 'Designer.SerializableDictionary`2[[System.Int32, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[Designer.PropertyValue, Designer, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]' in Assembly 'Designer, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' is not marked as serializable.

I have no problems with importing/exporting XML using LoadFromXml and SaveToXML after handling the DeserializeTag and SerializeTag events. (see posting http://mindfusion.eu/Forum/YaBB.pl?board=fcnet_disc;action=display;num=119616009...) - My ShapeNode tag objects are set to a serializable object that contains a SerializableDictionary object with a value that's a serializable object... - in otherwords, all my custom objects should be serializable.

I realize that I need to write a handler for SerializeControl and DeserializeControl, but do not know how to proceed. Could you please advise?

I guess the class I'm using is a bit out of the norm for serialization. In .NET the Dictionary class is not serializable, so I ended up creating an SerializableDictionary class that implements the IXMLSerializable interface (here's where I got the code:
http://weblogs.asp.net/pwelter34/archive/2006/05/03/444961.aspx )  In this case, I did not need to mark my class with [Serializable()].

But I took your advice and went ahead and added the [Serializable()] marking to the SerializableDictionary class:
*****
[XmlRoot("dictionary")]
[Serializable()]
    public class SerializableDictionary<TKey, TValue>

       : Dictionary<TKey, TValue>, IXmlSerializable

    {...}
*****
and the result was this error:

Type 'MindFusion.Diagramming.Shape' in Assembly 'MindFusion.Diagramming, Version=5.0.3.20676, Culture=neutral, PublicKeyToken=a0d18338041985ba' is not marked as serializable.

It's definitely that Dictionary object that's making all the trouble. I'm thinking I might need to use another lookup/hash object to implement my logic.

Thanks for the quick response!

I just ended up writing my own event handlers to cut/copy/paste on selected ShapeNodes in the diagram.

Thanks!