Specifying GNOME's screens [was Re: patch to gnome-session: smooth fade on logout]

[Bill Haneman <Bill Haneman Sun COM>]

This would, of course, break fullscreen magnification since one of the 
screens
will be used for the magnifier.  At  the moment we get around this by 
disabling
the logout fade if the 'accessibility' gconf key (which really means 
"assistive technology
support") is TRUE.

Though there are other reasons why the fade conflicts with GOK and 
gnopernicus
(mostly the use of server grabs), I think we need some way of specifying 
which
screens (on a multi-screen system) are "managed by GNOME", and restrict 
our fade
to those screens.  After all, there are people using _truly_ mixed 
environments, custom
apps or even cde on one screen, and GNOME on another.

At the moment I think the "gnome apps" that would need to respect such a 
setting
are:

metacity (don't post windows to non-GNOME screens; ideally, don't manage 
windows on
   non-GNOME screens, though I am not sure it's possible to run two WMs 
in one server)
nautilus (don't put a nautilus 'desktop' on non-GNOME screens)
panel (don't put panels on non-GNOME screens)
logout (don't fade non-GNOME screens)

However we don't want to go to extremes and (for instance) try to 
prevent gtk+ from drawing
to non-GNOME screens,  the need is just to keep GNOME "desktop" elements 
from taking over "reserved" screens.

The primary accessibility issue here is with fullscreen magnification, 
which needs one screen
to itself.

- Bill

> Nifty stuff.  For your next hack could you try to get the fade out
> effect to affect both screens on a dual screen system?  This bug has
> been sitting around at http://bugs.gnome.org/show_bug.cgi?id=117623 for
> ages new, since (IIRC) gnome 2.4 :(
>
> Alan
>
>