Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!sdd.hp.com!ucsd!ucbvax!Eng.Sun.COM!argv
From: argv@Eng.Sun.COM (Dan Heller)
Newsgroups: comp.windows.x.motif
Subject: Re: Problems after XtDestroyWidget
Message-ID: <9008151744.AA20679@turnpike.Eng.Sun.COM>
Date: 15 Aug 90 17:44:17 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: inet
Organization: The Internet
Lines: 74

On Aug 14, 12:36pm, Kee Hinckley wrote:
> > -- My List dialog frequently coredumps when I select
> > items a number of times.
> Given how close 1.1 is I'm tending to ignore problems that are
> clearly memory/pointer based.
I do, too -- but chances are that all of them won't be caught.
Someone once suggested that the entire motif library should be
compiled and run with Saber-C.  That should eliminate most of
the problems.

> I haven't had any problems at all with paned window though.
Are you running an R3 or R4 server?  I'm using an R4 server
on a sun 3/60.  Even backwards-compatibility mode doesn't help.
The code looks ok, but I still get the protocol error.

> >   I see a lot of questions going on that are
> > not getting answered or even replied to in any way.
> I don't know.  For a non-supported newsgroup with a lot of people
> without support contracts I think that OSF has been pretty good
> about giving feedback.  I've just assumed that most of the stuff
> I've seen that wasn't answered probably addresses problems no one has
> solved yet.

You're probably right -- and please keep in mind that this was
never intended as a flame.  If problems can't be solved, that's
one thing, but I am concerned that people are getting questions
answered directly to do them and the rest of us aren't getting
the benefits of their answers.

For example, I have a question :-)

There doesn't seem to be any way for to "replace" an item in
an XmList widget.  In order to do that, I have to:

void
reset_item(list, item, set_selected)
Widget hdr_list;
int item;
Boolean set_selected;
{
    XmString str;

    XmListDeletePos(list, item+1);
    str = XmStringCreateLtoR(generate_new_text(), charset);
    XmListAddItemUnselected(list, str, item+1);
    XmStringFree(str);
    if (set_selected)
        XmListSelectPos(list, item+1, False);
}

This is incredibly ugly both for the programmer to the user.
The list appears to clumsily delete the item and add the new
item.  Also, because of the activity, the list scrolls in
one direction or another and does not end up in the same order
as it was in beforehand.  There is no way to "get" the top or
bottom item in the list even though the data is saved in the
list data sturcture.

I am considering that the best way to do this is to maintain
a static copy of the list and whenever an item changes, the
entire list be reset using XmNlistItems.  This will provide
better visual feedback for the user, but has the cost of a
great deal of memory alloocation and freeing as well as the
text-to-compound string conversion.  The larger the list gets,
the worse this problem it becomes.

Has anyone run into this and conceived of possible solutions
that I haven't thought of?

-- 
dan
----------------------------------------------------
O'Reilly && Associates   argv@sun.com / argv@ora.com
Opinions expressed reflect those of the author only.