Undo/Redo error with Layouts

I have a Windows project that I upgraded to Go from a previous version and I am now getting an error when I try to undo or redo any of the layouts. The layouts work but on undo or redo I get an Index was out of Range error: Must be non negative or less than the size of the collection. This occurred in your GoDocument ChangeValue routine - not in my code.

I then tried to run your Layout Demo that came with Go 4.0 and on undo I get the exact same error in the same ChangeValue routine.
For now I am going to skip the undo manager on layouts but I would like to resolve this problem. I do not know how to approach fixing it since it happens down in the undo code.

We actually found this problem earlier this week. Fixed in 4.1, due out mid-March.