Path: utzoo!attcan!uunet!husc6!bloom-beacon!gatech!ncar!ames!pasteur!ucbvax!hplabs!hp-pcd!hpcvlx!fred
From: fred@hpcvlx.HP.COM (Fred Taft)
Newsgroups: comp.windows.x
Subject: Re: XtGetValues() and XtMoveWidget()
Message-ID: <1610031@hpcvlx.HP.COM>
Date: 15 Aug 88 15:40:08 GMT
References: <7266@burdvax.PRC.Unisys.COM>
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Lines: 17


When using XtGetValues(), you need to remember that there are two ways to
have the resulting value returned:

   1) It will be returned in the arglist's value slot, if this value has
      been set to NULL before the call to XtGetValues().

   2) It will be returned in the location pointed to by the address stored
      in the arglist's value slot, if this value has been set to a non-NULL
      value before the call to XtGetValues().

In your case, for the first call, the value has been set to NULL, so 
XtGetValues() returns the queried value in the arglist.  However, for the
second call, you now have a non-NULL value in your arglist, so the toolkit
assumes that you have supplied a pointer to a variable into which the
value is to be stored; thus, it is not surprizing that your program dumps
core!