Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!pepe!shane
From: shane@pepe.cc.umich.edu (Shane Looker)
Newsgroups: comp.sys.mac.programmer
Subject: Re: LightSpeed C query (DA with LSC)
Message-ID: <509@mailrus.cc.umich.edu>
Date: 13 May 88 19:09:08 GMT
References: <597@tasis.utas.oz> <0WWkiAy00XcP0GR2Yn@andrew.cmu.edu>
Sender: usenet@mailrus.cc.umich.edu
Reply-To: shane@pepe.cc.umich.edu (Shane Looker)
Organization: University of Michigan Computing Center, Ann Arbor
Lines: 21

In article <0WWkiAy00XcP0GR2Yn@andrew.cmu.edu> rs4u+@andrew.cmu.edu (Richard Siegel) writes:
>
>Because Desk Accessories use A4 as the base for globals, instead of A5, the
>QuickDraw globals will not be initialized properly. You should not use
>QuickDraw globals from a desk accessory or device driver, for this reason.

Here is a semi-related piece of trival about A4.  If you have a UserItem
in a dialog box the drawing procedure gets called from the ToolBox.  When
it gets called, A4 is not the same was when you called ModalDialog.  This
is quite alarming when you need to get at your Globals from inside the
procedure, AND  you are in a DA (driver).  The solution to the problem is
to put the value of A4 into the dataHandle of the the dialog box (it may 
either need to be extended or created), then MODIFY A4 while you are in 
the procedure, and replace it when you exit.

Fun Stuff.

Shane Looker
shane@pepe.cc.umich.edu 
uunet!umix!pepe.cc.umich.edu!shane
Looker@um.cc.umich.edu