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From: rlh2@ukc.ac.uk (Richard Hesketh)
Newsgroups: comp.windows.x
Subject: Re: Widget Refreshing Values !
Message-ID: <5195@harrier.ukc.ac.uk>
Date: 28 Jul 90 08:51:52 GMT
References: <9007271833.AA26394@metropolis.super.org>
Reply-To: rlh2@ukc.ac.uk (Richard Hesketh)
Organization: Computing Lab, University of Kent at Canterbury, UK.
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In article <9007271833.AA26394@metropolis.super.org> dsseewe@SUPER.ORG (Daniel Seewer) writes:
>
>   I have noticed a problem updating the values of several widgets
>(mostly labels) during one of my callback routines.

This is a feature of how Xt does its refreshing of a widget after a SetValues
call.  If the widget indicates that it requires updating after the SetValues
call then the Intrinsics clears the widgets window, which generates an
expose event that causes the widget to be *later* redrawn.

>Must I dispatch events during this "Big loop" to guarantee updates?

Essentially yes.  There are two general approaches to what you are doing.
You can either get some events and dispatch them during your "Big loop",
at a convenient point:

	while (XtAppPending(app_context)) {
		XEvent ev;

		XtAppNextEvent(app_context, &ev);
		(void)XtDispatchEvent(&ev);
	}

Or you make your "Big loop" a sub-process, with i/o via pipes etc.,
which leaves the event processing loop to carry on doing its job.
The pipe i/o can be handled as an extra event source thus leaving you
with only one event processing loop.  I find this a much better approach
because it allows you to separate the user interface from the application
in a fairly clean manner.  It also looks really neat when you can cut and
paste from output windows while still doing some number crunching 8-).

>			Dan Seewer
>			(dsseewe@super.org)

Richard Hesketh   :   @nsfnet-relay.ac.uk:rlh2@ukc.ac.uk
		  :   rlh2@ukc.ac.uk    ..!mcsun!ukc!rlh2
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