Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ll-xn!delaney
From: delaney@XN.LL.MIT.EDU (John R. Delaney)
Newsgroups: comp.sys.mac.hypercard
Subject: openStack & closeStack side effects
Keywords: side effects, timing
Message-ID: <1333@xn.LL.MIT.EDU>
Date: 29 Mar 89 00:33:24 GMT
Organization: MIT Lincoln Laboratory, Lexington, MA
Lines: 32

I would like to verify some Hypertalk semantics that I find odd (and
inconvenient).

When you close a stack (by going to another stack or whatever), is
there an implicit "unlock screen" command? Does it occur before or
after the associate "closeStack" message handlers are executed? Is
there also an implicit "unlock screen" command when you open a stack?
And when does it occur?

I THINK there are such implicit commands and that they occur before the
"closeStack" message handler execute and after the "openStack" message
handlers. If so, I would like to argue for changing the timing to
reverse the orders of the implicit "unlock screen" and message handler
executions. If not, then I am having some very peculiar problem I will
have to chase down.

Why do I care? My stack in this case wants to alter which of N
background radio buttons its highlighted as I go from card to card
depending on a background field's contents on the displayed card. When
I close a card, I turn off whatever radio button is on. When I open a
card, I turn on the desired radio button. To make the transition
visually smooth, I lock the screen before turning the one radio button
off and unlock the screen after turning the other radio button on. It
is straight-forward (if non-intuitive) to make transitions smooth
when a new card is created (with a default radio button on) and when a
card is deleted. But I cannot make the transition smooth when I open
and close the stack; there is always a period when no button is
highlighted as the stack is openned and as it is being closed.

Why do I care about something so modest? I am a perfectionist.

John