That was my initial suggestion. Add aproperty to the textbox to hold the control source. What I guessed would have allowed the use of the current ControlSource property then create the now property on the fly. Clever use of JustStem and JustExt since the field name is the surrogate filename extension.

>Actually, I hard-wired a property to hold the controlsource. And I made some evil misuse of JUSTSTEM and JUSTEXT (heh heh). I sent it to you.
>
>>>Already on it's way --- bear in mind that this is proof of concept. Also, I forget to say in the email, you set the controlsource at design time as you would any other bound control. The control itself swaps out the CS and maintains the value and the updating of the controlsource source value.
>>>
>>Let me take a wild guess here. You put something in the INIT like:
>>
>>This.AddProperty('cSource', This.ControlSource)
>>
>>Then in the Refresh:
>>
>>This.Value = eval(This.cSource)
>>
>>In the LostFocus:
>>
>>replace (This.cSource) with This.Value
>>
>>You, of course, probably dressed each method code to test for existence, etc.