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From: meth@research.att.COM
Newsgroups: comp.windows.x
Subject: (none)
Message-ID: <8711102209.AA13305@ATHENA.MIT.EDU>
Date: Tue, 10-Nov-87 12:26:00 EST
Article-I.D.: ATHENA.8711102209.AA13305
Posted: Tue Nov 10 12:26:00 1987
Date-Received: Fri, 13-Nov-87 03:25:59 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 70

VERSION:
        X11 release 1 (Actually Beta release of toolkit.)
SYNOPSIS:
        I have run into a philosophical problem with the geometry
        management scheme. Currently a child widget may request
        to be a certain size from its parent, but a parent
        has no way to request its children for their preferred sizes.
DESCRIPTION:
        The following scenario exemplifies the problem.
        Consider building a menu widget consisting of a "Menu" managing
        widget and smart "Label" widgets.  The smart label
        widget can produce  one line labels, and can
        detect mouse events.

        A menu is constructed by attaching several labels to a parent
        Menu widget. ( More generally attaching any type
        of widget to the menu widget.) A Trivial example is shown.
        
                 _____________
                |             |
                | Menu Widget |
                |_____________|
                  |  | ... |
                  |  |     |
           _______|  |     |
           |         |
           |         |
        ___|___    __|____
       |       |  |       |
       | LABEL |  | LABEL |
       |_______|  |_______|

        Now consider the following scenario: There are three labels
        "VIOLET and MAROON", "BLUE", and "GREEN" and a request comes
        to modify the first label to "RED". What we want to happen is shown
        in the next illustration.


         ___________________             _______
        | VIOLET and MAROON |           | RED   |
        |-------------------|           |-------|
        | BLUE              |   =====>  | BLUE  |
        |-------------------|           |-------|
        | GREEN             |           | GREEN |
        |-------------------|           |-------|
        
         Before                         After Label Has been Changed.

        
        Currently, the toolkit does not provide a clean way to
        do this for general widgets. That is one can implement this
        quite easily for one's own set of widgets, but the scheme will
        not work for a general set of widgets. Since these types of
        operations would frequently be needed, the the toolkit should
        provide a mechanism for allowing a parent to request
        its children what size they would like to be.

        One way to do this is to enter some new fields in the core
        widget definition, which would specify preferred sizes. Another
        is to provide a function  which a parent can call to find
        out about its children's preferences.
FIX:
        See above.


Marcel Meth			(201) 582-3142
AT&T Bell Laboratories		research!meth
office 2c535
600 Mountain Avenue
Murray Hill, NJ  07974