Re: adding session-management to a wm

[cannam all-day-breakfast com]

Tom Tromey <tromey@cygnus.com> writes:
> >>>>> "Chris" == Chris Cannam <cannam@all-day-breakfast.com> writes:
> 
> Chris> The wm surely can't make any association
> Chris> between previous and new instantiations of a client [...]
> Chris> unless it is a session manager itself... can it?
> 
> Nope, there's no way to do this.  It seems unbelievable to me
> right now (maybe it's too late at night?), but there it is.

If this is really true, then it's something of a bummer.  It's
all very well for a session manager to reopen all your windows
for you when you next log in, but it's not going to be any fun
if they all arrive in one big gloop on the default desktop.

Making the wm a session manager would be one answer (maybe the
gnome session manager should just be a library that any wm can
link against, and the gnome-session program itself could only
start if no wm has already taken the job?) but it's not wholly
satisfactory either.

There are various possible hacks of course -- e.g. the wm could
save associations of geometry, title & desktop; when it next
starts, any windows that are already open (or that open within,
say, the first half a minute) and that match on geometry and
title could be assumed to be the same apps as before and placed
on the "correct" desktop.  Ugly and unprincipled, but it could
probably be made to work most of the time.

I'd guess the trouble is just that the inventors of the protocol
assumed the window manager and session manager would be one and
the same.  Either way, unless I'm missing something obvious,
we're going to have to invent a simple workaround because
otherwise a lot of the appeal of session-management is going
to be completely lost.  I don't think I'd rush to use a session
manager that couldn't even start my apps up in the right places.


Chris