This thread is very interesting for me because I suggested something
about TIB_LookupCombo and NULL values a vew months ago:

Let's stay at the pizza topping example: nothing, bacon, cheese.

The topping-lookup table contains *two* entries: bacon and cheese and
so they are displayed in the TIB_LookupCombo. Ok.

If the user doesn't want any topping s/he has to press <DEL> while the
TIB_LookupCombo is focused.

I don't think that this is very intuitive and my customers seem to
think similar because I'm asked again and again how to remove a
previously selected item from a lookup combo so that the associated
column gets NULL.

I would prefer a property in TIB_LookupCombo 'EmptyString' where one
can enter a string (i.e. "<none>") which is displayed in the combo so
the user can select it. And the result is a NULL value in the
associated column.
No need to insert a NULL entry in the lookup table.

The RxDBLookupCombo from the Rx Library behaves exactly like that.
I have used this component a lot in the old days of BDE programming.

Any comments are appreciated.

Mario

--- In IBObjects@y..., "Jason Wharton" <jwharton@i...> wrote:
> As a general rule I expect there to be no NULL states when
incremental
> searching is involved.
> I don't plan to do anything special to accommodate it.
>
> Jason Wharton
> CPS - Mesa AZ
> http://www.ibobjects.com
>