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From: ephraim@Think.COM (Ephraim Vishniac)
Newsgroups: comp.sys.mac.programmer
Subject: How's the screen cleaned after _SysError?
Message-ID: <34252@news.Think.COM>
Date: 26 Feb 90 18:49:46 GMT
Sender: news@Think.COM
Reply-To: ephraim@Think.COM (Ephraim Vishniac)
Organization: Thinking Machines Corporation, Cambridge MA, USA
Lines: 17

How is the screen restored after a call to _SysError?

Before you say, "There is no 'after' _SysError," please note that the
disk-swap alert is displayed by _SysError.  A little creeping around
with Macsbug informs me that there's a low-mem global called DSWndUpdate,
but I haven't puzzled out how it's used or what it does.

The reason I'm asking about this is that I'd like to be able to display an
alert at just about any time (much like the disk-swap alert, and for
similar reasons) and then clean up nicely.  Right now, I'm waiting for the
next call to _GetOSEvent and using _PaintBehind to get the alert rect
redrawn.  This works, but it's not as smooth as whatever the disk-swap code
does.
Ephraim Vishniac    ephraim@think.com   ThinkingCorp@applelink.apple.com
 Thinking Machines Corporation / 245 First Street / Cambridge, MA 02142
        One of the flaws in the anarchic bopper society was
        the ease with which such crazed rumors could spread.