Thanks for the confirmation. I think this issue is subtle enough to
warrant some additional explanation in the specification.
> >3. Thre is no way of specifying the Actionslots for an initially
> > empty cell. As a work-around, I would suggest using
> > ObjectNumber 0 to represent 'no initial contents' in
> > TokenGroupItems.
>
> That's true. I remember that someone suggested to be able to fill the
> tokenGroupItems list with null in order to define actionslots to an
> initially empty listGroup. This could be a new suggestion for the WG12
> recommendations.
I suggested using NULL some time ago, but I think that was felt to be
undesirable as it would require a slight alteration to the syntax. Now
I suggest using a known dummy ObjectReference instead, just as a
convenient convention.
Also the subject of TokenGroupItems: the activation behaviour of
TokenGroup inherited by ListGroup causes all the visibles in
TokenGroupItems to be activated. However in ListGroup, the control over
the visibility of items should be transferred to the Update behaviour.
The current situation means that the visibles are all placed on the
screen momentarily, before they are immediately reorganised into their
list positions. This could look a bit ugly. Wouldn't it make more sense
for ListGroup to override this this part of the TokenGroup activation
behaviour?
Regards,
Richard
-- ----------------------------------------------------------------- Richard Houldsworth, Software Engineer, Philips Research Laboratories, Redhill, Daytime phone number: +44 (0)1293 815052 RH1 5HA E-mail: richardh@prl.research.philips.com