The char set-up works fine but, when I enter a numeric code in the operator text box, the combo is displayed in selected highlight, but with no text showing. I f I do it slowly in debug, I can se the combo, remaing unselected, with the correct val in, then it flips to the above.

This tells me that the value that you are assigning to the combo box cannot be found in its internal list.

Did you initialize the combo's value property to 0 in the property sheet and did you set its BoundTo property to .T. ?