I had the same problem, opening the queries in the OnFormShow instead
of the OnFormCreate solved it. It has to do with some timing I think.
The first tabsheet contained the master data and the second tabsheet
the detail data. The problem only occured when the second tabsheet
(with the detail data) was shown for the second time without scolling
the detail data after it was showed the first time.

Regards,

Wilbert

--- In IBObjects@y..., "Jason Wharton" <jwharton@i...> wrote:
> UpdateScrollBar makes a call using the handle of the grid control.
Opening
> the dataset most likely is triggering this to take place. If
somehow you can
> determine when the control is actually visible we can probably
suppress that
> call until it is visible and the problem will be resolved totally.
Then we
> need a notification that it is now visible and the scrollbar needs
to be
> updated accordingly.
>
> Anyone got some time to snoop into this? I'm busy endeavoring to,
drum roll
> please, release IBO4 today.
>
> Regards,
> Jason Wharton
> CPS - Mesa AZ
> http://www.ibobjects.com
>
>
> ----- Original Message -----
> From: "Lester Caine" <lester@l...>
> To: "IBO" <IBObjects@y...>
> Sent: Wednesday, July 18, 2001 12:14 PM
> Subject: [IBO] Disappearing Grids in IBO4
>
>
> > Jason
> >
> > I thought I should post this here, as a pointer to others.
> >
> > I created a test setup for the problem and off cause it
> > would not go wrong.
> >
> > So I took it a bit further and found my problem.
> >
> > The grids in question are set up on TTabSheet pages, and the
> > relevent tables are opened and closed with the TabSheet Show
> > and Hide. The problem was that the show for the first page
> > happens before the form is being displayed. While it was not
> > a problem with IBO3.6, IBO4 seems to get upset.
> >
> > All I had to do was use my 'started' flag to prevent the
> > early open, and then open properly in FormActivate.
> >
> > I suspect that the problem is related to the setting of the
> > parameters for query, as these are not set when the first
> > Show was activated, working from the design mode settings.
> > So wether IBO4 needs to have them set, or just needs to wait
> > until the grid exists before opening the query I am not
> > sure, I can't get the simple test to go wrong even though I
> > know what fixes it.
> >
> > --
> > Lester Caine
> > -----------------------------
> > L.S.Caine Electronic Services
> >
> >
> >
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >