Most likely a bug.
Another workaroud is to remove goEdit (?) form the ValuListEditor's Options property.
The problem is the fact tha an active Editor is shown, and this plays havoc with the ValueListEditor.
If you study it's code you can see multiple attempts to fix that.
Apparently not all is covered (sigh).
Please rettest with trunk before you file a bugreport.
Also, if you file a bugreport, attach a minimal test case, so strip everything away that does not have any influence on the bug in quenstion.
Bart