Thanks for that explanation Richard. I finally get the difference between sharedBehavior and backgroundBehavior. Seems like sharedBehavior is the one to use for everything except old HC stacks.
On Tue, Mar 3, 2015, 7:14 AM Richard Gaskin <ambassa...@fourthworld.com> wrote: > Stephen Goldberg wrote: > > > I think the bottom line is to be cautious about putting mouseUp > > scripts in background groups, or to put a disclaimer in the group > > at the beginning of the group handler the line (as mentioned in > > the User Manual (pg 131, 5.3.9): > > > > if the owner of the target is not me then pass mouseUp > > The backgroundBehavior property is a tricky thing, implemented for > compatibility with imported HyperCard stacks but given the differences > between the HC and LC object models it's always going to be at least a > little mind-bending. > > In HC, there was always and only one background, which was placed below > the card. > > In LC, there is no "background" object pe se, but instead employs groups > which can be shared across cards. In LC we can have any number of > groups, and they may even be nested. > > In LC, in the absence of an always-present background object, all > objects always reside on the card. > > To maintain compatibility with HC, the backgroundBehavior was introduced > in an attempt to account for those cases where the message handling > order needed the background after the card, as it was in HC, rather than > before the card as is natural in LC. > > In older versions of LC setting the backgroundBehavior was the only way > to share groups among multiple cards, which sometimes caused problems > for developers expecting the natural order of messages to be in play, > reflecting the visual order in which all controls, even groups, are on > top of the card. > > So a few versions back a new property was added: the sharedBehavior. > When true this allows us to share a group across multiple cards, and > when creating a new card any groups with their sharedBehavior set are > automatically placed on new cards. It's related to the > backgroundBehavior, but is not the same thing: > > When the backgroundBehavior is set, the sharedBehavior is also set. > This should trigger the change you're describing, in which messages are > handled by as group with the backgroundBehavior set occur after the card > receives them. > > But the sharedBehavior can be set by itself, allowing sharing without > altering LC's natural message order as reflected by what we see visually > on screen: objects on top of the card get messages before the card does. > > So all that said, we might consider what you're seeing to be a bug. > > But personally, with more than a decade separating me from the last time > I had a machine even capable of running HC, it's been so long since I've > thought about the HC-style message order that I never rely on it. I was > very glad when they introduced the sharedBehavior as a way of sharing > groups while maintaining the natural, visible order of messages, and > when I need messages to occur after the card I generally just put them > in the stack or a library. > > But there are those who may need the older HC-style message order, and > if so that's what the backgroundBehavior is supposed to provide. > > If you see a difference between LC and HC with message flow when the > backgroundBehavior is set, it may be time to file a bug report. > > -- > Richard Gaskin > Fourth World Systems > Software Design and Development for the Desktop, Mobile, and the Web > ____________________________________________________________________ > ambassa...@fourthworld.com http://www.FourthWorld.com > > _______________________________________________ > use-livecode mailing list > use-livecode@lists.runrev.com > Please visit this url to subscribe, unsubscribe and manage your > subscription preferences: > http://lists.runrev.com/mailman/listinfo/use-livecode > _______________________________________________ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
