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From: mikey@eukanuba.wpd.sgi.com (Mike Yang)
Newsgroups: comp.windows.x.motif
Subject: Re: callbacks for text widget
Keywords: text,callback,reason
Message-ID: <1990Sep18.162031.10832@relay.wpd.sgi.com>
Date: 18 Sep 90 16:20:31 GMT
References: <14983@gouda.quad.com> <1990Sep16.004605.9095@relay.wpd.sgi.com> <829@auto-trol.UUCP>
Sender: news@relay.wpd.sgi.com ( CNews Account )
Reply-To: mikey@sgi.com
Organization: Silicon Graphics, Inc.
Lines: 31

In article <829@auto-trol.UUCP>, marbru@auto-trol.UUCP (Martin Brunecky) writes:
|>     [ Plus, I am a firm believer that Xt was invented to RELIEF an
|>       application programmer from looking at X events. Thus, even though
|>       Motif blindly follows DECwindows in passing events to the callback,
|>       I don't ever use those. One of reasons of having a widget is
|>       to hide underlying X input system from an application. This,
|>       however, puts a little more responsibility on a widget writer, so
|>       that applications don't have to compensate for poor widget by
|>       knitting a whole net of workarounds based on X calls around it].

I agree with you.  For the common case, the point of Xt and Motif is to
hide the need for Xlib knowledge from the developer.  However, it would
be a big mistake to make the knowledge completely inaccessible and thus
limit the ability of Xt/Motif programs.

For instance, when dealing with ICCCM selections a timestamp is needed
Since many of the Motif callbacks provide the event structure, this
can be used for a timestamp for, say, owning the selection when a
list box item is chosen.

If the Motif callbacks didn't provide this extra information, I'd have
to use something like CurrentTime, and in the ICCCM viewpoint, I would
be a\ bad boy.

So I'm thankful that although I don't often need the event field, it's
usually there when I do need it.  (I say "usually" because it's not
there when a text selection is made -- Grrr.)

-----------------------------------------------------------------------
                 Mike Yang        Silicon Graphics, Inc.
               mikey@sgi.com           415/335-1786