[dapper] log out dialog takes ages to appear on thin clients

Hi,

on a thin client with a constrained network (10Mbps or 100 Mbps with many thin clients), the Ubuntu logout dialog can take up to 30 seconds to appear after it has been clicked in the "System" menu. During this time, the thin client is totally unresponsive and seems to be frozen to the novice user.

I think this is because the background fading is quite network intensive.
reverting the gconf key /apps/panel/global/upstream_session to True totally fixes the problem, even on slooow thin clients. The upstream GNOME log out dialog appears immediately (because it doesn't fade the screen at all...).

The should be a way to disable the "fade" effect, to continue to use the ubuntu log out dialog which is nicer than the upstream one on slow terminal and/or constrained networks.