Newsgroups: comp.windows.x
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!mintaka!bloom-beacon!dont-send-mail-to-path-lines
From: gildea@expo.lcs.mit.EDU (Stephen Gildea)
Subject: Re: save_under quiz for xperts!
Message-ID: <9105201954.AA14669@alex.lcs.mit.edu>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: X Consortium, MIT Laboratory for Computer Science
References: <9105172046.AA01600@cas.org>
Date: 20 May 91 19:54:20 GMT
Lines: 21

    If you have save_under specified for a popup window and the
    contents of the window under the popup changes, what is the
    correct behavior for a server when the popup is unmapped?

    A) Restore the contents of the window under the popup, thus losing the
       changes made while the window was obscured?

    B) Recognize the contents were changed and send an expose event to the
       window.

There is at least one other option, which the MIT sample server uses:

C) Keep track of the changing contents (as if the obscured window had
   backing store) and restore those contents when the popup is
   unmapped.  No expose events are sent.

Remember, if it truly supports save unders, the server should not be
sending expose events.  Thus neither A nor B is a proper solution.   

 < Stephen
   MIT X Consortium