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From: jkjl@munnari.oz (John Lim)
Newsgroups: comp.sys.mac
Subject: Re: Moire bug with MS Word 3.02
Message-ID: <2423@munnari.oz>
Date: 4 Oct 88 00:34:10 GMT
References: <2420@munnari.oz>
Organization: Comp Sci, Melbourne Uni, Australia
Lines: 31

> in article <882@hub.ucsb.edu>, steveg@squid.ucsb.edu (Steve Greenland) says:
>> 
>> I've come across an interesting bug involving Moire 2.12 (recently
>> posted to comp.binaries.mac) and MS Word 3.02.  If you are in the 
>> "Page Preview" mode of Word and Moire is activated (either through
>> timeout or by putting the mouse cursor in the upper right corner of
>> the screen), when you try to go back to Word, the system will crash. 

I first tried to reproduce this bug under MF. Page Preview worked fine. Then
I switched over to UniFinder and whammo - the mac crashed with a mem full error.

What happened was that Word continiously polls the front window. When a window
has to be updated in page preview mode, what word thinks is the front window
is redrawn. It so happens that moire's window has been disposed but Word still
thinks that moire is the front window. So when it tries to redraw the front
window, it attempts to draw into an 'infinitely' large region, and there isnt
enough memory for that.

In technospeak and C, this is what happens in MS-Word 3.02:
	/* Moire activates */
	frontWind = FrontWindow();
	/* Moire deactivates and frontWind points to rubbish */
	
	BeginUpdate(frontWind);  /* Word crashes as frontWind is invalid */
	Redraw(frontWind);
	EndUpdate(frontWind);

I have fixed this in Moire 2.2. I will post this version as soon as it has
been tested.

	john lim