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From: cmcclary@bronze.ucs.indiana.edu (Charles McClary)
Newsgroups: comp.sys.mac.programmer
Subject: Problem with GetNextEvent trap patch in MultiFinder
Message-ID: <1991Jan15.200340.28431@bronze.ucs.indiana.edu>
Date: 15 Jan 91 20:03:40 GMT
Sender: news@bronze.ucs.indiana.edu (USENET News System)
Organization: Indiana Univeristy
Lines: 72

I am trying to patch the GetNextEvent trap A970.  My test patch 
seems to work correctly in Finder, but not in MultiFinder.  In 
MultiFinder, when a desktop icon (disk icon) is covered up by a 
volume or folder window and the window is then moved to uncover 
the icon, the portion of the desktop icon which was covered remains 
invisible.  This does not happen in finder.  Below is the source code 
for the patch.  I am using Think C 4.0.  What an I leaving out?

Thanks in advance,

Charles McClary
Indiana University
cmcclary@bronze.ucs.indiana.edu


/*************  Patch to GetNextEvent  **********/
#include <SetUpA4.h>

#definenil0L

#defineGetNextEventTrap0xA970

longoldGetNextEvent;
Str255trash;

pascal Boolean NewGetNextEvent(int eventMask, EventRecord 
*theEvent);
void main(void);

pascal Boolean NewGetNextEvent(eventMask, theEvent)
inteventMask;
EventRecord* theEvent;
{
SetUpA4();

CallPascalB(eventMask, theEvent, oldGetNextEvent);

RestoreA4();
}

void main()
{
HandlemyHandle = nil;
PtrmyPtr;
SysEnvRecworld;
Str255*namePtr;

asm
{
move.l A0, myPtr
}
RememberA0();
SetUpA4();
if (!Button())
{
myHandle = RecoverHandle(myPtr);
DetachResource(myHandle);

oldGetNextEvent = NGetTrapAddress(GetNextEventTrap, 
ToolTrap);
NSetTrapAddress(NewGetNextEvent, GetNextEventTrap, 
ToolTrap);
}
RestoreA4();
}


Charles McClary
Workstations Division
University Computing Services
Indiana University
cmcclary@bronze.ucs.indiana.edu