Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!bu-cs!dartvax!Jim.Matthews
From: Jim.Matthews@dartvax
Newsgroups: comp.sys.mac.programmer
Subject: Re: driver windows (was notification manager)
Message-ID: <16166@dartvax.Dartmouth.EDU>
Date: 16 Oct 89 21:01:27 GMT
References: <2903@netcom.UUCP> <31889@ucbvax.BERKELEY.EDU>
Sender: news@dartvax.Dartmouth.EDU
Reply-To: Jim.Matthews@dartvax
Organization: Dartmouth College
Lines: 21

In article <31889@ucbvax.BERKELEY.EDU>, oster@dewey.soe.berkeley.edu (David
Phillip Oster) writes:
> Note that a driver and a desk accesoory are essentially the same thing. If
> you set the needTime bit in the driver header, then the system will call
> the driver's Ctl entry point with an accRun message. At that point you can
> safely put up a window. 

I guess it depends on what you consider "safe".  Under MultiFinder, when
your driver gets the accRun call the current heap and window layer will be
those of the current application -- you may want your window to show up in
front of everything but you should be very careful about allocating memory
in someone else's application heap.  Furthermore, the current resource chain
will be that of the current app -- just because you have an open resource
file doesn't mean that you can get to it at accRun time.

These gotchas are documented (somewhat incompletely) in a recent tech note.
It seems clear that Apple does not want drivers opening windows, allocating
memory, or doing anything else of substance at accRun time.
--
Jim Matthews
Dartmouth College