Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!bloom-beacon!EXPO.LCS.MIT.EDU!rws
From: rws@EXPO.LCS.MIT.EDU
Newsgroups: comp.windows.x
Subject: Re: mystery window unseen by twm
Message-ID: <8905301212.AA03758@expire.lcs.mit.edu>
Date: 30 May 89 12:12:06 GMT
References: <2405@titan.sw.mcc.com>
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 7


    I had thought that transient windows were for
    use by things like pop-up menus and confirmer panels, which typically would
    not be managed by the window manager.

You are confusing transient-for windows and override-redirect windows.
Read the ICCCM.