Path: utzoo!utgpu!news-server.csri.toronto.edu!orasis.vis.toronto.edu!tjhorton
Newsgroups: comp.windows.x.motif
From: tjhorton@vis.toronto.edu ("Timothy J. Horton")
Subject: Re: How to re-manage the same child widget
Message-ID: <91May16.183920edt.8838@orasis.vis.toronto.edu>
Organization: Department of Computer Science, University of Toronto
References: <9105132043.AA11128@11128> <91May15.224003edt.8838@orasis.vis.toronto.edu> <1991May16.154512.23319@thyme.jpl.nasa.gov>
Distribution: inet
Date: 16 May 91 22:39:25 GMT
Lines: 40

kaleb@thyme.jpl.nasa.gov (Kaleb Keithley) writes:
>tjhorton@vis.toronto.edu ("Timothy J. Horton") writes:
>>jerryl@is.Morgan.COM (Jerry Liebelson) writes:
>>>  QUESTION:  Is there an efficient, trouble-free way to unmanage and
>>>re-manage one instance of this XmList under different parent container
>>>widgets, which themselves might be contained within different shell widgets?
>>
>>XtReparent (I think that's what it's called -- no books nearby).
>
>This fits into the category of dis-information.  There is no XtReparent().
>And there is no easy, nor clean way to reparent widgets.  This is not my
>opinion, but an echo of something Schliefer/Gettys/Converse/et. al. have
>said in months gone by.

I believe you.  Sorry, I guess I was confusing it with the Xlib call for
reparenting windows (not widgets).  XReparent or XReparentWindow or whatever.

>One possible solution would be to GetValues() the XmNitems resource from 
>one and SetValues() it onto the other.  Since this is fast and simple, 
>it's the way I would go.

This won't answer Jerry's question; his list is very large and he wants only
one instance of the XmList.  He'll have several copies because XtSetValues on
the XmNitems resource causes a list widget to allocate and make a copy of the
entire list.

If you no longer need access to the list that you provided to a list widget,
you can destroy it, because the list widget has its own private copy.  Most
motif widgets are like this; they reallocate copies of whatever you give them
via pointers.  Furthermore, if you fetch back resource values via pointers,
most widgets allocate yet another copy of the resource and pass back the new
copy, which you normally have to free explicitly.

I had an application in which I needed to very quickly swap large lists in
and out of a list widget, but couldn't, because the dang list widget always
freed its old list and allocated and copied the new one.  I had to write my
own code from scratch to display selection lists without copying them.

[Sorry for the earlier disinformation, and thanks for catching it]
Tim