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From: sokoloff@athena.mit.edu (James T Sokoloff)
Subject: Re: Unexpected Update Events
Message-ID: <1991Apr29.224424.14447@athena.mit.edu>
Sender: news@athena.mit.edu (News system)
Organization: Massachusetts Institute of Technology
References: <11082@bunny.GTE.COM> <1991Apr29.170744.12029@news.iastate.edu>
Date: Mon, 29 Apr 91 22:44:24 GMT
Lines: 26

> doesn't GetNextEvent remove the event?
> Do you HAVE to use the BEGIN UPDATE and END UPDATE procedures to
> get it to stop?

No, Update Events are no queded in the fashion of all the level 3-5
events.  Update events(priority level 2) are generated when there are
no higher level events to return.  Update events are generated by the
system in real-time (At the call to GNE, WNE) and not when the call to
InvalRgn() or InvalRect() is executed)

Yes, you HAVE to call BeginUpdate() & endupdate()  Actually, I don't see
any reason for not wanting to do so.  These calls make life much easier
by setting up the visRgn to some intelligent region for the update.

Neither call requires vast knowledge of the Mac.  They are easy to use
and very helpful...  Please, save yourself some time and just use
the calls provided for you...

Cheers,
Jim Sokoloff

PS: No flames; I know you don't actually HAVE to call begin & end update;
you could call ValidRgn/Rect, but this is much more difficult to explain, and
has only limited usefullness (esp. to beginners who just want things to
work in a non-coplicated manner)