Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!apple!oliveb!intelca!mipos3!omepd!psu-cs!sagar
From: sagar@psu-cs.UUCP (Arun Sagar)
Newsgroups: comp.sys.mac.programmer
Subject: SrollRect Hassles
Message-ID: <1733@psu-cs.UUCP>
Date: 4 Mar 89 23:22:50 GMT
Distribution: usa
Organization: Dept. of Computer Science, Portland State University; Portland OR
Lines: 23


Hi,
	This may be a stupid question, but i haven't found a satisfactory explanation yet. I am using:
MacII w/ 4bit video card, 1Meg, LSC3.01, Sys/Find6.01.

When i try the following:

SetPort(currentPort);
ScrollRect(&currentPort->portRect,dh,dv,NULL);

....

	it scrolls alright, but doesn't erase the region that it left behind
like it says in IM-I.

When i try:

ScrollRect(&currentPort->portRect,dh,dv,updateRgn);
EraseRgn(updateRgn);

	it does what i want it to do.  Any idea what's up? I don't know what's happening, but do recall that before i *debugged* my code, i didn't need that EraseRgn() call.

sagar@psu-cs.