Re: Google to launch PC operating system

[Alan Mackenzie]

Hyman Rosen <hyrosen@mail.com> wrote:
> Alan Mackenzie wrote:
>>> [1]  KDE and Gnome are _not_ window managers.

>> :-)  OH YES THEY ARE!!!  They perform the function that ratpoison or fvwm
>> do, don't they?  Or do you mean that I could run ratpoison as window
>> manager, then start GNOME or KDE "I'm not a window manager" in it?

>> I've never been too clear about this.  I've never come across any clear
>> explanation, and never been interested enough actively to seek it out.

> The X Window Protocol has a SubstructureRedirect event that an X
> client can request to handle on a window.

Bit of trouble parsing this.  Mainly with the words "has" and "on".
What is the thing that is being handled?  What is agent is doing the
handling?  In what sense does this take place "on" a window?  To what
does the X client issue the request?  What is the nature of the request?
Is it the client requesting permission to do the handling?

> Only one client may have
> this event requested on a window - a second one who tries to request
> it fails.

Can't parse this either.  In what sense does a client "have" an event
requested?  Does this mean it causes something else to request the event?
What does it mean to "request" an event?  I know that events can be
signalled, and that they can be handled, but how can they be requested?

> Window managers request this event for the root window;

Still can't parse this; is the object of the sentence "this event for
the root window", i.e. when the event is directed at the root window, or
is it "this event", i.e. the window manager is acting at the direction of
the root window.

Sorry, it's late Friday afternoon.

> as a result, various attempts to do things to windows get mapped to
> requests sent to the window manager, which can do a variety of things
> with them.

Ah, OK.  I think.

> Thus, an X client program can see if there's a window manager already
> running by seeing whether its attempt to request SubstructureRedirect
> events succeeds or fails. Sufficiently clever clients can then run in
> two modes depending on this. I assume the KDE and GNOME environments
> might be such sufficiently clever programs.

I've kind of lost it.  How does this relate to the question of whether or
not KDE and GNOME are window managers?

-- 
Alan Mackenzie (Nuremberg, Germany).