Pager/switcher per workspace or per screen

Metacity has had a number of requests to allow alt-Tab to show all
windows on the current screen and not just the windows on the current
workspace/desktop:

http://bugzilla.gnome.org/show_bug.cgi?id=143511

The pager already has this ability, but has no way to communicate it
to the WM. It seems that the best way to deal with this is a new EWMH
hint so that it can be done in a cross-WM way.

I think this is closely allied to desktop arrangements, and propose
that the currently unused data.l[1] in _NET_NUMBER_OF_DESKTOPS be 1 if
switching should be per screen, and 0 (the default, as at present) if
it should be per workspace/desktop. The patches given on the bug above
are a basic implementation this (which still has a few bugs), and
there is also a program to switch between switching per workspace and
per screen.

I'd like feedback on whether this is the best way or whether it would
be better to introduce a whole new hint.

peace

T