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From: cheshire@neon.Stanford.EDU (Stuart David Cheshire)
Newsgroups: comp.sys.mac.programmer
Subject: VBL tasks
Message-ID: <1991May13.014725.5238@neon.Stanford.EDU>
Date: 13 May 91 01:47:25 GMT
Organization: Computer Science Department, Stanford University, Ca , USA
Lines: 23

Quick question / plea for help:

Does anybody know how to stop Multifinder turning off my VBL task when my
application is switched to the background?

The technical notes proudly explain this wonderful feature of Multifinder
which means you don't have to set up A5 to point to your globals -- but I
am using the VBL task for timing and I do set up A5 correctly and I don't
want it to slow down whenever my app is in the background (major OR minor
context switches have this effect, so even when the app is 'in the fore-
ground' the speed is erratic).

I tried doing as they say and installing the vbl task in the system heap
which is supposed to stop this, but it doesn't seem to work:

task = (ex_VBLTask*) NewPtrSysClear(sizeof(ex_VBLTask));
task->task.qType    = vType;
task->task.vblAddr  = (ProcPtr)Tick;
task->task.vblCount = 1;
task->regA5         = Application_A5;
VInstall(task);

Please e-mail respones to cheshire@cs.stanford.edu