1) You might do something like this:

if ((diagram as IItemFactory).TypeTable[typeof(IconNode)] == null)
     Diagram.RegisterItemClass(typeof(IconNode), "IconNode", 0);

2) If you don't want it serialized, you could simply not call the Register method. You can access ClsidTable and TypeTable as shown above - they are Hashtable objects - and remove the type from the first table and the id from the second table.

I hope that helps,
Stoyan

This is something you can do only once for the application lifetime, you do not have to register the custom types with each Diagram instance.

I hope that helps,
Stoyan

This is something you can do only once for the application lifetime, you do not have to register the custom types with each Diagram instance.

I hope that helps, 
Stoyan

I know that Register is done once in the life time of an application. i was asking about UN register( removal from hash table). Do i have to do this with all instances of Diagram class?