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From: pim@ele.tue.nl (Pim Buurman)
Newsgroups: comp.windows.x.motif
Subject: XtGetValues gives Segmentation fault
Message-ID: <554@al.ele.tue.nl>
Date: 14 Sep 90 15:08:31 GMT
Sender: news@eba.eb.ele.tue.nl (The News system)
Organization: Eindhoven University of Technology, The Netherlands
Lines: 64

I have a problem with the following widget-tree
(only the interesting parts are shown).

object	main_window : XmMainWindow {
	arguments { XmNmenuBar	   = command; };
	controls {
	  XmMenuBar 	    command;
	  XmScrolledWindow  scrollwindow;
	};
	callbacks {
	  MrmNcreateCallback = procedure create_proc (k_main_window);
	};
};

object	scrollwindow : XmScrolledWindow {
	arguments {
          XmNverticalScrollBar = XmScrollBar  scrollbar;
	  XmNworkWindow = space;
	};
	controls {
	  XmDrawingArea space;
	  XmScrollBar	scrollbar;
	};
	callbacks {
	  MrmNcreateCallback = procedure create_proc(k_scrollwindow);
	};
};

object	space : XmDrawingArea {
	callbacks {
	  MrmNcreateCallback = procedure create_proc(k_space);
	  XmNexposeCallback = procedure exposed(k_space);
	  XmNinputCallback = procedure button_handler(k_space);
	};
};

The first time when exposed is called, it crashes in XtGetValues
with a segmentation fault on our Apollo DN3000:

void exposed(w, tag, reason)
Widget		w;
int		*tag;
XmDrawingAreaCallbackStruct	*reason;
{
	Arg		wargs[2];
	Dimension	width, height;

	XtSetArg(wargs[0], XmNwidth, &width);
	XtSetArg(wargs[1], XmNheight, &height);
	XtGetValues(scrollwindow, wargs, 2);

I have tried several things, like changing scrollwindow to a
BulletinBoard, etc. Nothing worked.
However, on our Alliant FX/8 XtGetValues returns a heigth 0
and a wrong width.
On our HP 9000/800 XtGetValues returns the RIGHT values.
I know, that the HP is too clever with function arguments.

My questions are:
1) Is the tree correct ?
2) Might there be a programming error (somewhere else) ?
3) Is there a bug in motif ? We currently use
   Motif 1.0.A on Apollo and Alliant (self compiled), and
   Motif 1.0 on HP (from HP).