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From: goodill_eric@tandem.com (Eric Goodill)
Newsgroups: comp.sys.mac.programmer
Subject: Summary and new question: lists in modal dialogs
Message-ID: <1991Jun28.183556.5127@tandem.com>
Date: 28 Jun 91 18:35:56 GMT
Sender: news@tandem.com
Organization: Tandem Computers
Lines: 47
Nntp-Posting-Host: suntan.tandem.com

Hi,

My original question was how do user items get redrawn when the dialog 
manager redraws the rest of a modal dialog.  There are two general answers.

1: Install a drawing procedure for the user item.  The handle that you 
pass with setDItem for a user item is in fact a pointer to a drawing 
routine.  IM-1 touches on this briefly, but tech note 34 goes into some 
detail.  The dialog manager calls your routine when it redraws the other 
parts of the dialog.

2: Use a modal dialog filter proc and handle the update events.  If you've 
got a user item that responds to mouse clicks (such as a list), then you 
almost for sure have a filter proc.  This proc gets all events that the 
dialog window gets before the dialog manager applies its standard filter 
proc.  Since the dialog is a window, it gets activate and update events.  
You can respond to the update event by drawing your user item.

BTW, user items seem to be a good way to draw the default button ring 
around the OK button.

So much for the summary.  I've gotten the code working, but in so doing a 
few new questions popped up.  My user item is a list using Apple's list 
manager.  I noted the following peculiar behavior.  If I didn't do a call 
to getDItem on the list user item, then when I called lUpdate in my filter 
proc (during an update event and passing dialogPtr^.visRgn), nothing got 
drawn.  I did not have to make a call to setDItem.  The getDItem is done 
even before the showWindow after reading the dialog in.  It used to be 
used when I had a list item drawing routine instead of responding to 
update events.  When I switched from a drawing proc to update events, I 
had left the drawing proc code in but just commented out the body of the 
proc.  All was well.  Then, convinced the new scheme worked, I removed the 
getDItem, setDItem pair and the drawing proc.  Then updates stopped 
working.  The list was just blank always.

I put the getDItem, setDItem pair back in and the drawing proc.  Then I 
removed the setDItem.  Updates worked again.  I then removed the drawing 
proc (cuz it's not getting called) and it still worked.  I removed the 
getDItem, and updates stopped working.

So I'm puzzled.  Use Macsbug, I know I was getting the correct activate 
and update events.  The update regions for the dialog window were not 
empty.  There were a simple box enclosing the whole window.  I'm using 
THINK Pascal 3.0.  IIci.  6.0.5.  Any ideas?

Eric Goodill, goodill_eric@tandem.com, Cupertino, California
"Sucks Syntax"  -- John Haskey