Fade to black in xscreensaver and Gnome

[Lukas Sabota]

I am having two different fade effects between xscreensaver and GNOME 
logout.  In xscreensaver, the screen smoothly fades to black.  When I 
logout with GNOME, my screen harshly changes though different shades of 
grey until the entire screen is faded.  I'm using the nvidia-glx 
driver.  If the fadeout can be as nice as it is in xscreensaver, why 
isn't it?

Lukas