Problem with undoManager on linkLabel

I have a flowLink between two activityNodes, inside a rack. when I drag the linkLabel I can’t do Undo. If I move by the keys, I can. And if I move the activityNodes I can do undo always. If I insert the activityNodes outside the rack, on the goView and move the linkLabel I can do undo always.
Any idea why I can’t do undo?
Thanks in advance.

Well, undo/redo seem to work for moves of labels in the Processor sample application. And I guess you are saying it works for you too, as long as the link isn’t part of a rack object.
What happens when the link connects one node that is outside of the rack and one that is inside it? Can you undo/redo then?
One way to debug this is to look at the GoChangedEventArgs that are being saved in the GoUndoManager:
public class SpecialUndoMgr : GoUndoManager {
public SpecialUndoMgr() {}
public override GoUndoManagerCompoundEdit CommitCompoundEdit(GoUndoManagerCompoundEdit cedit) {
foreach (IGoUndoableEdit e in cedit.AllEdits) {
System.Diagnostics.Trace.WriteLine(cedit.PresentationName + " " + cedit.AllEdits.Count.ToString() + " changes");
return cedit;
Caution: this can generate a lot of trace output.