BGs

[Jeanne A. E. DeVoto]

At 1:21 PM -0700 4/3/05, Dan Shafer wrote:
>Copying a background from one card to another *duplcates* the 
>background so that changes made to one of them will not be reflected 
>in the copy. Placing a background seems to me to at least imply that 
>the author intends for the background to be shared so that changes 
>to the background made from any card will be reflected in all other 
>cards on which the background appears. To make that happen, the 
>group must be set to behave as a background.

Actually, this isn't so - a group can be shared without having its 
backgroundBehavior property set to true. Shared groups worked fine 
even before the backgroundBehavior property was added to the 
language. What backgroundBehavior does is cause shared groups to be 
automatically placed on new cards, as well as tweaking the message 
path for the group so it matches HyperCard's behavior more closely.

(My only excuse for not documenting that "place" turns on 
backgroundBehavior is that no one told me about the change, and I 
didn't stumble across it on my own when the property was added. If I 
had been told about it, I would have argued that it was a bug, not a 
feature. Commands shouldn't spew side effects like that, even if 
they're documented. As it is, apparently if you want a shared group 
whose backgroundBehavior property is false, you need to remember to 
reset the property after every time you place the group on a card.)

The whole situation with backgroundBehavior is confusing. It was 
added in order to better emulate HyperCard backgrounds, which it 
does, but there were collateral changes (for example, changes to what 
"the backgroundNames" means) that resulted in, IMHO, a mess.
-- 
jeanne a. e. devoto ~ revolution at jaedworks.com
http://www.jaedworks.com