Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!husc6!purdue!decwrl!asente
From: asente@decwrl.dec.com (Paul Asente)
Newsgroups: comp.windows.x
Subject: Re: XtCallbackNone etc.
Message-ID: <988@bacchus.dec.com>
Date: 13 Dec 88 22:07:41 GMT
References: <8812111548.AA07300@tub.UUCP>
Organization: DEC Western Software Lab
Lines: 17

In article <8812111548.AA07300@tub.UUCP> net@TUB.BITNET (Oliver Laumann) writes:
>I don't understand the rationale behind the functions XtCallbackNone,
>XtCallbackNonexclusive, XtCallbackExclusive, and XtCallbackPopdown.
>Why are they called `callback' functions and why would one want to use
>these functions instead of XtPopup and XtPopdown?
>
>Usually, `callback functions' are provided by an application programmer
>and called by the code implementing a widget.  The above mentioned
>functions, however, are exported by the Toolkit.  Should they be put
>into a callback list, and if so, into which one?

These are just convenience functions for the programmer.  If all your
callback routine needs to do is call XtPopup or XtPopdown, you can put
XtCallback{None, Nonexclusive, Exclusive, Popdown} in the callback list
and avoid having to write the function.

	-paul asente
	    asente@decwrl.dec.com	decwrl!asente