groups and background

Dar Scott dsc at swcp.com
Sat Dec 28 12:06:01 EST 2002


On Friday, December 27, 2002, at 03:28 PM, J. Landman Gay wrote:

> In HyperCard "the number of backgrounds" always returns the number of 
> backgrounds in the stack, since backgrounds are members of the stack. 
> Revolution's terminology needs to differentiate between all available 
> groups in the stack, and those which are simply placed on the current 
> card. "The number of backgrounds" will always refer to the number of 
> total groups in the stack.

I got numbers that are not consistent with this.  (see my mail 
yesterday)  I think "the number of backgrounds" refers to total number 
of groups directly on or placed on cards of the stack.  I suspect that 
nested groups are not counted.  I will have to run more tests to be sure.


> It gets more complicated if there are several groups on a card. In that 
> case, once the message goes through the group and reaches the card, it 
> is then sent to all other groups on the card whose backgroundBehavior 
> is true -- as though there were, perhaps, several "layers" of 
> backgrounds behind the card. (At least, I think that's how it works; 
> I'd have to test it, so take this part with a grain of salt.)

UDI ran the experiment and reported the results this past week; that 
does not seem to be the case.  (See UDI mail with "[7]" on about the 
20th.)

Only the card and controls placed directly on the card see groups with 
background behavior set behind (after) the card in their paths.  (Uh.  
UDI's experiments did not show "only", that was my limited experiments.)


I see the above confusion as evidence that "background" related concepts 
are confusing and inconsistent.


Thanks for the information on the HyperCard history.  I had learned some 
of that but didn't have the more complete picture.  I fully recognize 
the historical basis for how things are, but this does not remove the 
pedagogical problems.  And the documentation, translation and plain ole 
programming confusion and added work.


Dar Scott









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