I probably should have mentioned that the control is really a cluster of controls, including many different control types. The control in question is a string control (string constant->change to control).
The problem is that the default value for a control is not saved as part of the typedef - or at least a part of the typedef that is enforced. As a result, if you change the default for a typedef, new instances of the typedef will show it but existing instances will not be changed.
So I have an enhancement request: I suggest adding to every control's "right-click" menu:
DataOperations->Reinitialize to typedef default
and have it greyed out for controls which have no associated typedef.
Thanks for the idea. I have filed a product suggestion with R and D with your recommendation.