Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!zaphod.mps.ohio-state.edu!usc!snorkelwacker!bloom-beacon!LARRY.MCRCIM.MCGILL.EDU!mouse
From: mouse@LARRY.MCRCIM.MCGILL.EDU (der Mouse)
Newsgroups: comp.windows.x
Subject: Re: ICCCM and colormaps---simple question
Message-ID: <9002161143.AA27262@Larry.McRCIM.McGill.EDU>
Date: 16 Feb 90 11:43:30 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 35

>> From the Xlib doc file in the R4 distribution:

>>	Multiple clients can select input on the same window. ...
>>	However, only one client at a time can select for
>>	SubstructureRedirectMask, ResizeRedirectMask, and
>>	ButtonPressMask.  If a client attempts to select any of these
>>	event masks and some other client has already selected one, a
>>	BadAccess error results.

> ButtonPressMask?????  Does this mean that if I have 3 xterms and no
> window manager running, only one xterm will respond properly to
> button presses?  That can't be right.  Can it?

Fortunately that is not correct.  The reason?  Each xterm is selecting
for ButtonPressMask on a different window.  The whole paragraph I
quoted is describing *per-window* restrictions.  You can have many
different clients selecting for ButtonPressMask, provided they are
asking for button presses from different windows.  (The same is
presumably true of the redirect masks, but it's probably less useful in
that case.)

Thus, if the xterms were asking for ButtonPressMask on the root window,
there would be a conflict.  But in reality, each xterm is selecting for
ButtonPressMask on is one of its own windows, so there's no problem.

The window manager discussion hasn't mentioned this explicitly, because
window managers almost have to ask for this sort of thing on the root.

I admit the paragraph I quoted could be clearer on this point.
(At least I didn't write it - it's not my fault :-)

					der Mouse

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