[compiz] metacity theme opacity

[David Reveman]

I pushed out some changes to gwd that makes it possible to properly set
an overall opacity value for any metacity theme. Making the complete
decorations translucent can look bad with some themes. However, I've
made it possible to have the opacity fade from opaque to the selected
opacity value in a similar way to how the built-in decorations look.
This usually looks a lot better.

I'll add a schema file for gwd sometime soon but you'll have to manually
add the gconf keys for now:

gconftool-2 -s /apps/gwd/metacity_theme_opacity -t float 0.75
gconftool-2 -s /apps/gwd/metacity_theme_shade_opacity -t bool TRUE
gconftool-2 -s /apps/gwd/metacity_theme_active_opacity -t float 0.75
gconftool-2 -s /apps/gwd/metacity_theme_active_shade_opacity -t bool TRUE

"active" options affects the active window decorations. "shade" options
toggles the fade from opaque to translucent.

I think this is the best we can do for opacity support in old metacity
themes. Once the new theme version lands in metacity [1], gwd will be
updated to support it and I'm hoping that this new version will include
support for real opacity.

[1] http://bugzilla.gnome.org/show_bug.cgi?id=102547

-David