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In the Editor Example ,if I Sellect All object on the model ,and I delete all.

If I click the Undo menuitem,  there is just one object undelete . How could I undelete all? 

The UnDo function seems only work on a object (element) once a time.

How could I fix it ? 

Thanks . 

By the way... 

In the sample "Editor Example" and "Diagram Studio" the Redo do nothing.

How could I fix it ? 

If I copy a Element , and I delete some element else . The Paste do nothing .

How could I fix it?

Thank you. 

Hello ,would you mind review this issue again ? I still have some strange problems with undo and redo .

The redo not always work fine. The undo can work with one element once a time. If I change more than one element ,how could I undo that by a "batch".

Thanks. 

If afraid this is a limitation of the undo/redo system in version 4.0. It cannot seperate undo/redo tasks by "command' only at the "element" level. This is something we will address in version 5.0.

You could write your own undo/redo system by serialising the model after each command you create and reserialising on undo/redo, but this would involve a bit of work on your part.

I have heard the answer I feel very helpless, The lack of this feature, users certainly unacceptable.

And my project very tight timetable, with great pressure, and if so it will fail.

If I write my own undo/redo system by serialising the model after each command. How about the movement of elements?

My suggestion here is to serialise the entire model after every action using a stream. This is the only way to implement your own undo/redo system without access to the source code.

This can be done by calling Diagram.Save/Load with a stream (you can used a compressed stream in .net 2.0)

 You can use the CurrentMouseElements property together with the mouse events to detect movement of items, the ElementInserted/ElementRemoved events and override the DoCommand method for other actions. Together with your custom code, this should provide coverage for all changes.

Hope this helps.