> As workaround I call TIB_Query's CalculateFields method in

TIB_DataSource's

> OnDataChange event.

That isn't a workaround, that is what I intend all to do.
The reason is there could be many other fields changing their values which
have nothing to do with what you calculated fields are based upon. To have
the calculated fields recomputed each time an unrelated field value is
changed is potentially a very unreasonable thing to do.

What probably should be done is come up with a way we know which columns
which calculated fields are dependant upon and have it do efficient
recalculating.

So, what you are confronting isn't a bug, it is a feature waiting to be
implemented.

Regards,
Jason Wharton
CPS - Mesa AZ
http://www.ibobjects.com