You may try: not tested
Create a special checkbox class. In its refresh put

is isNull(this.value)
   this.value = 0
   nodefault
endif

>Hi, Sergey
>
>I do not think so, because I need the checkbox to show, but I need it to show the correct value, i.e. unchecked for 0 or .NULL.
>
>Thanks anyway.
>>
>>Would DynamicCurrentControl work for you?
>>