Undo operation causing ArgumentOutOfRang

I'm receiving the following error periodically when I call Undo. Any idea why this is happening?
System.ArgumentOutOfRangeException' in northwoods.go.dll
Additional information: Specified argument was out of the range of valid values.

I haven’t seen that error in years, since when we were implementing undo/redo support long before we first released any version of GoDiagram.
It’s likely the error is occuring in some implementation of GoObject.ChangeValue, as an undo is being performed on a GoChangedEventArgs. Can you narrow down the kind of operation that you are undoing?

This is want I've narrowed it down to so far.
When this transaction is complete and I try to do an UNDO the exception is thrown.
this.Changed(0, 0, 0, this.Bounds, 0, 0, this.Bounds);
this.Text = dlg.NodeName;
this.Label.TextColor = dlg.NodeColor;
this.Label.Font = dlg.NodeFont;
this.Description = dlg.NodeDescription;
this.Document.FinishTransaction("Node properties changed");
I forgot to mention...
dlg.NodeFont is returning type System.Drawing.Font
dlg.NodeColor is returning type System.Drawing.Color

I haven’t tried that code, but that call to Changed(0, …) looks suspicious. Try removing that line.
What class is this code defined in? What version of GoDiagram Win(?) are you using?

I'm using Win 2.1.2 and I have several classes. The base class for the above example is GoIconicNode. I have several custom properties that I have added to the class and their values are being changed in between the StartTransaction() - FinishTransaction() calls. Could this be causing a problem? I've tried adding a Changed(...) call with values of the changed custom properties but the same exception is being thrown.
If I remove calls to Changed(...) the exception is still thrown. The only time it is not thrown is if I only modify a property that is in GoIconicNode, not in my derived class.
Hope that helps!

Well, you must be referring to the Description property, which I assume is something you defined. Then the error is raised by GoObject.ChangeValue, when it sees a hint value that it doesn’t recognize.
You just need to override ChangeValue to handle your particular “ChangedDescription” hint case. There are lots of examples of this in the sample applications.