Path: utzoo!attcan!uunet!husc6!bloom-beacon!ATHENA.MIT.EDU!swick
From: swick@ATHENA.MIT.EDU (Ralph R. Swick)
Newsgroups: comp.windows.x
Subject: Re: question regarding toolkit callback functions
Message-ID: <8807181258.AA10443@LYRE.MIT.EDU>
Date: 18 Jul 88 12:58:01 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Organization: DEC/MIT Project Athena
Lines: 37


     Date:  Sun, 17 Jul 88 19:52:12 EDT
     From:  sundar@wheaties.ai.mit.edu (Sundar Narasimhan)
     
     a.
     I have an application that has a rather complicated function bound to
     a command button's callback. Since this function takes a long time,
     ideally I would like to be able to provide feedback to the user at
     intermediate points ... Now, the way the toolkit functions are
     set up, one would have to write one's own XtMainLoop()/select() to do this, am
     I right? (or is there some other way of intercepting this loop)? 

In general yes, you will need to include your own XtNextEvent/
XtDispatchEvent code within your compute-bound function if the
application is single threaded.  For many things, you can get away with
merely processing Exposure events using XCheckIfEvent/XtDispatchEvent.

     Currently, I get to seeing only the last of the update status
     messages.. XFlush() doesn't help.

I don't understand why.  If you're not reading events, XFlush is the
correct way to make sure new requests are dequeued from the client.

     b. Regarding translation tables: How does one invoke a function normally
     in a translation table of a widget from within a program? For example,
     I would like to scroll a text window's display one page up from
     within my program.

There is at present no way to invoke a widget's Action routines without
an input event.  Widgets are expected to export public procedures to do
this (which will frequently be wrappers around their Actions).

                         I know this is kind of a pain, but people, could
     everyone garbage collect their mailing lists at least once in a while ...
     Thanks.

Amen.