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From: converse@EXPO.LCS.MIT.EDU (Donna Converse)
Newsgroups: comp.windows.x
Subject: Re: Problem with asciiTextWidget callback
Message-ID: <9005071524.AA15637@expo.lcs.mit.edu>
Date: 7 May 90 15:24:31 GMT
References: <9005062345.AA03834@aps2.spa.umn.edu>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: X Consortium, MIT Laboratory for Computer Science
Lines: 39


> I am trying to register a callback with the asciiTextWidget.  I create
> the widget, then add a callback with XtAddCallback.
>
>  When I execute the code, I get a message:
>    
> Warning: Cannot find callback list in XtAddCallbacks

The Athena asciiText widget is composed of the Text, AsciiSrc, and AsciiSink
widgets.  The callback resource of the asciiText widget is actually a 
resource of the AsciiSrc widget (noted under "callback" in section 5.5.1).

When XtAddCallback is called, no callback resource is found in the
asciiText widget, so your callback is not registered.

Section 5.5 explains that these resources which actually belong to the
AsciiSrc or AsciiSink can be set via XtSetValues, or at widget creation
time (i.e. with XtCreateManagedWidget).  So, the following will work:



  static XtCallbackRec	cb[] = {
      {Text_Callback,		(XtPointer) NULL},
      {(XtCallbackProc) NULL,	(XtPointer) NULL}
  };

  top = XtInitialize (argv[0],"TEst", NULL, 0, &argc, argv);


  string = XtVaCreateManagedWidget ("string",
				    asciiTextWidgetClass,
				    top,
				    XtNstring, "test",
				    XtNeditType, XawtextEdit,
				    XtNcallback, cb);


Donna Converse
converse@expo.lcs.mit.edu