>>try "set confirm on"
>
>no effect. I did manage to get it to stay in the textbox, but once the value = .NULL., it won't hold a different value. After adding a check in the gotfocus method, I was able to stay in the textbox and edit, but it reverted to null after moving to another control, so once a null value is ever entered, it cannot be changed to something else
>

This sounds like it dates back to the beginning of Xbase when doing a GET on a field with an empty string would just skip past that field. I think to get around this, you can't bind the textbox directly to the field if you want to accept nulls in the field. Use a form property instead, and if the field is null, you'll have to pad it out with spaces so the user can actually enter something. How are you making a distinction in appearance between spaces and a null?